The Earth straddling the limb of the Moon, as seen from above Compton crater on the lunar farside, taken by the Lunar Reconnaissance Orbiter spacecraft. Credit: NASA/GSFC/Arizona State University.
Nearly 47 years ago, the crew of Apollo 8 took an image of planet Earth from the Moon that has been called “the most influential environmental photograph ever taken.” Called Earthrise, the picture represented the first time human eyes saw their homeworld come into view around another planetary body.
Phobos and Deimos, photographed here by the Mars Reconnaissance Orbiter, are tiny, irregularly-shaped moons that are probably strays from the main asteroid belt. Credit: NASA - See more at: http://astrobob.areavoices.com/2013/07/05/rovers-capture-loony-moons-and-blue-sunsets-on-mars/#sthash.eMDpTVPT.dpuf
Many of the planets in our Solar System have a system of moons. But among the rocky planets that make up the inner Solar System, having moons is a privilege enjoyed only by two planets: Earth and Mars. And for these two planets, it is a rather limited privilege compared to gas giants like Jupiter and Saturn which each have several dozen moons.
Whereas Earth has only one satellite (aka. the Moon), Mars has two small moons in orbit around it: Phobos and Deimos. And whereas the vast majority of moons in our Solar System are large enough to become round spheres similar to our own Moon, Phobos and Deimos are asteroid-sized and misshapen in appearance.
At one time, astronomers believed the surface of Mars was crisscrossed by canal systems. This in turn gave rise to speculation that Mars was very much like Earth, capable of supporting life and home to a native civilization. But as human satellites and rovers began to conduct flybys and surveys of the planet, this vision of Mars quickly dissolved, replaced by one in which the Red Planet was a cold, desiccated and lifeless world.
However, over the past few decades, scientists have come to learn a great deal about the history of Mars that has altered this view as well. We now know that though Mars may currently be very cold, very dry, and very inhospitable, this wasn’t always the case. What’s more, we have come to see that even in its current form, Mars and Earth actually have a lot in common.
Between the two planets, there are similarities in size, inclination, structure, composition, and even the presence of water on their surfaces. That being said, they also have a lot of key differences that would make living on Mars, a growing preoccupation among many humans (looking at you, Elon Musk and Bas Lansdorp!), a significant challenge. Let’s go over these similarities and the difference in an orderly fashion, shall we?
Sizes, Masses and Orbits:
In terms of their size and mass, Earth and Mars are quite different. With a mean radius of 6371 km and a mass of 5.97×1024 kg, Earth is the fifth largest and fifth most-massive planet in the Solar System, and the largest of the terrestrial planets. Mars, meanwhile, has a radius of approximately 3,396 km at its equator (3,376 km at its polar regions), which is the equivalent of roughly 0.53 Earths. However, it’s mass is just 6.4185 x 10²³ kg, which is around 10.7% that of Earth’s.
Artistic representation of the orbits of Earth and Mars. Credit: NASA
Similarly, Earth’s volume is a hefty 1.08321 x 1012 km3, which works out 1,083 billion cubic kilometers. By comparison, Mars has a volume of 1.6318 x 10¹¹ km³ (163 billion cubic kilometers) which is the equivalent of 0.151 Earths. Between this difference in size, mass, and volume, Mars’s surface gravity is 3.711 m/s², which works out to 37.6% of Earths (0.376 g).
In terms of their orbits, Earth and Mars are also quite different. For instance, Earth orbits the Sun at an average distance (aka. semi-major axis) of 149,598,261 km – or one Astronomical Unit (AU). This orbit has a very minor eccentricity (approx. 0.0167), which means its orbit ranges from 147,095,000 km (0.983 AU) at perihelion to 151,930,000 km (1.015 AU) at aphelion.
At its greatest distance from the Sun (aphelion), Mars orbits at a distance of approximately 249,200,000 km (1.666 AU). At perihelion, when it is closest to the Sun, it orbits at a distance of approximately 206,700,000 km (1.3814 AU). At these distances, the Earth has an orbital period of 365.25 days (1.000017 Julian years) while Mars has an orbital period of 686.971 days (1.88 Earth years).
However, in terms of their sidereal rotation (time it takes for the planet to complete a single rotation on its axis) Earth and Mars are again in the same boat. While Earth takes precisely 23h 56m and 4 s to complete a single sidereal rotation (0.997 Earth days), Mars does the same in about 24 hours and 40 minutes. This means that one Martian day (aka. Sol) is very close to single day on Earth.
Earth’s axial tilt (or obliquity) and its relation to the rotation axis and plane of orbit. Credit: Wikipedia Commons
Mars’s axial tilt is very similar to Earth’s, being inclined 25.19° to its orbital plane (whereas Earth’s axial tilt is just over 23°). This means that Mars also experiences seasons and temperature variations similar to that of Earth (see below).
Structure and Composition:
Earth and Mars are similar when it comes to their basic makeups, given that they are both terrestrial planets. This means that both are differentiated between a dense metallic core and an overlying mantle and crust composed of less dense materials (like silicate rock). However, Earth’s density is higher than that of Mars – 5.514 g/cm3 compared to 3.93 g/cm³ (or 0.71 Earths) – which indicates that Mars’ core region contains more lighter elements than Earth’s.
Earth’s core region is made up of a solid inner core that has a radius of about 1,220 km and a liquid outer core that extends to a radius of about 3,400 km. Both the inner and outer cores are composed of iron and nickel, with trace amounts of lighter elements, and together, they add to a radius that is as large as Mars itself. Current models of Mars’ interior suggest that its core region is roughly 1,794 ± 65 kilometers (1,115 ± 40 mi) in radius, and is composed primarily of iron and nickel with about 16-17% sulfur.
Both planets have a silicate mantle surrounding their cores and a surface crust of solid material. Earth’s mantle – consisting of an upper mantle of slightly viscous material and a lower mantle that is more solid – is roughly 2,890 km (1,790 mi) thick and is composed of silicate rocks that are rich in iron and magnesium. The Earth’s crust is on average 40 km (25 mi) thick, and is composed of rocks that are rich in iron and magnesium (i.e. igneous rocks) and granite (rich in sodium, potassium, and aluminum).
Artist’s impression of the interior of Mars. Credit: NASA/JPL
Comparatively, Mars’ mantle is quite thin, measuring some 1,300 to 1,800 kilometers (800 – 1,100 mi) in thickness. Like Earth, this mantle is believed to be composed of silicate rock that are rich in minerals compared to the crust, and to be partially viscous (resulting in convection currents which shaped the surface). The crust, meanwhile, averages about 50 km (31 mi) in thickness, with a maximum of 125 km (78 mi). This makes it about three times as hick as Earth’s crust, relative to the sizes of the two planets.
Ergo, the two planets are similar in composition, owing to their common status as terrestrial planets. And while they are both differentiated between a metallic core and layers of less dense material, there is some variance in terms of how proportionately thick their respective layers are.
Surface Features:
When it comes to the surfaces of Earth and Mars, things once again become a case of contrasts. Naturally, it is the differences that are most apparent when comparing Blue Earth to the Red Planet – as the nicknames would suggest. Unlike other planet’s in our Solar System, the vast majority of Earth is covered in liquid water, about 70% of the surface – or 361.132 million km² (139.43 million sq mi) to be exact.
The surface of Mars is dry, dusty, and covered in dirt that is rich iron oxide (aka. rust, leading to its reddish appearance). However, large concentrations of ice water are known to exist within the polar ice caps – Planum Boreum and Planum Australe. In addition, a permafrost mantle stretches from the pole to latitudes of about 60°, meaning that ice water exists beneath much of the Martian surface. Radar data and soil samples have confirmed the presence of shallow subsurface water at the middle latitudes as well.
As for the similarities, Earth and Mars’ both have terrains that varies considerably from place to place. On Earth, both above and below sea level, there are mountainous features, volcanoes, scarps (trenches), canyons, plateaus, and abyssal plains. The remaining portions of the surface are covered by mountains, deserts, plains, plateaus, and other landforms.
Mars is quite similar, with a surface covered by mountain ranges, sandy plains, and even some of the largest sand dunes in the Solar System. It also has the largest mountain in the Solar System, the shield volcano Olympus Mons, and the longest, deepest chasm in the Solar System: Valles Marineris.
Earth and Mars have also experienced many impacts from asteroids and meteors over the years. However, Mars’ own impact craters are far better preserved, with many dating back billions of years. The reason for this is the low air pressure and lack of precipitation on Mars, which results in a very slow rate of erosion. However, this was not always the case.
Mars has discernible gullies and channels on its surface, and many scientists believe that liquid water used to flow through them. By comparing them to similar features on Earth, it is believed that these were were at least partially formed by water erosion. Some of these channels are quite large, reaching 2,000 kilometers in length and 100 kilometers in width.
Color mosaic of Mars’ greatest mountain, Olympus Mons, viewed from orbit. Credit NASA/JPL
So while they look quite different today, Earth and Mars were once quite similar. And similar geological processes occurred on both planets to give them the kind of varied terrain they both currently have.
Atmosphere and Temperature:
Atmospheric pressure and temperatures are another way in which Earth and Mars are quite different. Earth has a dense atmosphere composed of five main layers – the Troposphere, the Stratosphere, the Mesosphere, the Thermosphere, and the Exosphere. Mars’ is very thin by comparison, with pressure ranging from 0.4 – 0.87 kPa – which is equivalent to about 1% of Earth’s at sea level.
Earth’s atmosphere is also primarily composed of nitrogen (78%) and oxygen (21%) with trace concentrations of water vapor, carbon dioxide, and other gaseous molecules. Mars’ is composed of 96% carbon dioxide, 1.93% argon and 1.89% nitrogen along with traces of oxygen and water. Recent surveys have also noted trace amounts of methane, with an estimated concentration of about 30 parts per billion (ppb).
Because of this, there is a considerable difference between the average surface temperature on Earth and Mars. On Earth, it is approximately 14°C, with plenty of variation due to geographical region, elevation, and time of year. The hottest temperature ever recorded on Earth was 70.7°C (159°F) in the Lut Desert of Iran, while the coldest temperature was -89.2°C (-129°F) at the Soviet Vostok Station on the Antarctic Plateau.
Space Shuttle Endeavor silhouetted against the atmosphere. The orange layer is the troposphere, the white layer is the stratosphere and the blue layer the mesosphere. Credit: NASABecause of its thin atmosphere and its greater distance from the Sun, the surface temperature of Mars is much colder, averaging at -46 °C (-51 °F). However, because of its tilted axis and orbital eccentricity, Mars also experiences considerable variations in temperature. These can be seen in the form of a low temperature of -143 °C (-225.4 °F) during the winter at the poles, and a high of 35 °C (95 °F) during summer and midday at the equator.
The atmosphere of Mars is also quite dusty, containing particulates that measure 1.5 micrometers in diameter, which is what gives the Martian sky a tawny color when seen from the surface. The planet also experiences dust storms, which can turn into what resembles small tornadoes. Larger dust storms occur when the dust is blown into the atmosphere and heats up from the Sun.
So basically, Earth has a dense atmosphere that is rich in oxygen and water vapor, and which is generally warm and conducive to life. Mars, meanwhile, is generally very cold, but can become quite warm at times. It’s also quite dry and very dusty.
Magnetic Fields:
When it comes to magnetic fields, Earth and Mars are in stark contrast to each other. On Earth, the dynamo effect created by the rotation of Earth’s inner core, relative to the rotation of the planet, generates the currents which are presumed to be the source of its magnetic field. The presence of this field is of extreme importance to both Earth’s atmosphere and to life on Earth as we know it.
Map from the Mars Global Surveyor of the current magnetic fields on Mars. Credit: NASA/JPL
Essentially, Earth’s magnetosphere serves to deflect most of the solar wind’s charged particles which would otherwise strip away the ozone layer and expose Earth to harmful radiation. The field ranges in strength between approximately 25,000 and 65,000 nanoteslas (nT), or 0.25–0.65 Gauss units (G).
Today, Mars has weak magnetic fields in various regions of the planet which appear to be the remnant of a magnetosphere. These fields were first measured by the Mars Global Surveyor, which indicated fields of inconsistent strengths measuring at most 1500 nT (~16-40 times less than Earth’s). In the northern lowlands, deep impact basins, and the Tharsis volcanic province, the field strength is very low. But in the ancient southern crust, which is undisturbed by giant impacts and volcanism, the field strength is higher.
This would seem to indicate that Mars had a magnetosphere in the past, and explanations vary as to how it lost it. Some suggest that it was blown off, along with the majority of Mars’ atmosphere, by a large impact during the Late Heavy Bombardment. This impact, it is reasoned, would have also upset the heat flow in Mars’ iron core, arresting the dynamo effect that would have produced the magnetic field.
Another theory, based on NASA’s MAVEN mission to study the Martian atmosphere, has it that Mars’ lost its magnetosphere when the smaller planet cooled, causing its dynamo effect to cease some 4.2 billion years ago. During the next several hundred million years, the Sun’s powerful solar wind stripped particles away from the unprotected Martian atmosphere at a rate 100 to 1,000 times greater than that of today. This in turn is what caused Mars to lose the liquid water that existed on its surface, as the environment to become increasing cold, desiccated, and inhospitable.
Satellites:
Earth and Mars are also similar in that both have satellites that orbit them. In Earth’s case, this is none other than The Moon, our only natural satellite and the source of the Earth’s tides. It’s existence has been known of since prehistoric times, and it has played a major role in the mythological and astronomical traditions of all human cultures. In addition, its size, mass and other characteristics are used as a reference point when assessing other satellites.
The Moon is one of the largest natural satellites in the Solar System and is the second-densest satellite of those whose moons who’s densities are known (after Jupiter’s satellite Io). Its diameter, at 3,474.8 km, is one-fourth the diameter of Earth; and at 7.3477 × 1022 kg, its mass is 1.2% of the Earth’s mass. It’s mean density is 3.3464 g/cm3 , which is equivalent to roughly 0.6 that of Earth. All of this results in our Moon possessing gravity that is about 16.54% the strength of Earth’s (aka. 1.62 m/s2).
The Moon varies in orbit around Earth, going from 362,600 km at perigee to 405,400 km at apogee. And like most known satellites within our Solar System, the Moon’s sidereal rotation period (27.32 days) is the same as its orbital period. This means that the Moon is tidally locked with Earth, with one side is constantly facing towards us while the other is facing away.
Thanks to examinations of Moon rocks that were brought back to Earth, the predominant theory states that the Moon was created roughly 4.5 billion years ago from a collision between Earth and a Mars-sized object (known as Theia). This collision created a massive cloud of debris that began circling our planet, which eventually coalesced to form the Moon we see today.
Mars has two small satellites, Phobos and Deimos. These moons were discovered in 1877 by the astronomer Asaph Hall and were named after mythological characters. In keeping with the tradition of deriving names from classical mythology, Phobos and Deimos are the sons of Ares – the Greek god of war that inspired the Roman god Mars. Phobos represents fear while Deimos stands for terror or dread.
Phobos measures about 22 km (14 mi) in diameter, and orbits Mars at a distance of 9,234.42 km when it is at periapsis (closest to Mars) and 9,517.58 km when it is at apoapsis (farthest). At this distance, Phobos is below synchronous altitude, which means that it takes only 7 hours to orbit Mars and is gradually getting closer to the planet. Scientists estimate that in 10 to 50 million years, Phobos could crash into Mars’ surface or break up into a ring structure around the planet.
Meanwhile, Deimos measures about 12 km (7.5 mi) and orbits the planet at a distance of 23,455.5 km (periapsis) and 23,470.9 km (apoapsis). It has a longer orbital period, taking 1.26 days to complete a full rotation around the planet. Mars may have additional moons that are smaller than 50- 100 meters (160 to 330 ft) in diameter, and a dust ring is predicted between Phobos and Deimos.
Scientists believe that these two satellites were once asteroids that were captured by the planet’s gravity. The low albedo and the carboncaceous chondrite composition of both moons – which is similar to asteroids – supports this theory, and Phobos’ unstable orbit would seem to suggest a recent capture. However, both moons have circular orbits near the equator, which is unusual for captured bodies.
So while Earth has a single satellite that is quite large and dense, Mars has two satellites that are small and orbit it at a comparatively close distance. And whereas the Moon was formed from Earth’s own debris after a rather severe collision, Mars’ satellites were likely captured asteroids.
Conclusion:
Okay, let’s review. Earth and Mars have their share of similarities, but also some rather stark differences.
Mean Radius: 6,371 km 3,396 km
Mass: 59.7×1023 kg 6.42 x 10²³ kg
Volume: 10.8 x 1011 km3 1.63 x 10¹¹ km³
Semi-Major Axis: 0.983 – 1.015 AU 1.3814 – 1.666 AU
Air Pressure: 101.325 kPa 0.4 – 0.87 kPa
Gravity: 9.8 m/s² 3.711 m/s²
Avg. Temperature: 14°C (57.2 °F) -46 °C (-51 °F)
Temp. Variations: ±160 °C (278°F) ±178 °C (320°F)
Axial Tilt: 23° 25.19°
Length of Day: 24 hours 24h 40m
Length of Year: 365.25 days 686.971 days
Water: Plentiful Intermittent (mostly frozen)
Polar Ice Caps: Yep Yep
In short, compared to Earth, Mars is a pretty small, dry, cold, and dusty planet. It has comparatively low gravity, very little atmosphere and no breathable air. And the years are also mighty long, almost twice that of Earth, in fact. However, the planet does have its fair share of water (albeit mostly in ice form), has seasonal cycles similar to Earth, temperature variations that are similar, and a day that is almost as long.
All of these factors will have to be addressed if ever human beings want to live there. And whereas some can be worked with, others will have to be overcome or adapted to. And for that, we will have to lean pretty heavily on our technology (i.e. terraforming and geoengineering). Best of luck to those who would like to venture there someday, and who do not plan on coming home!
This illustration shows Earth surrounded by filaments of dark matter called “hairs. A hair is created when a stream of dark matter particles goes through the planet. A new study proposes that Earth and the other planets are filled with “hair”. Credit: NASA/JPL-Caltech
I’m losing mine, but the Solar System may be way hairier than we ever thought, with thick crops of filamentary dark matter streaming through Earth’s core and back out again even as you read this.
Estimated distribution of matter and energy in the universe. Credit: NASA
A new study publishing this week in the Astrophysical Journal by Gary Prézeau of NASA’s Jet Propulsion Laboratory proposes the existence of long filaments of dark matter, or “hairs.” Dark matter is a hypothetical form of matter that emits no light, thereby resisting our attempts to see and photograph it, but based on many observations of its gravitational pull on ordinary matter, astronomers have measured the amount of dark matter to an accuracy of 1%.
Massive amounts of it formed a tangled web of filaments after the Big Bang and ensuing epoch of cosmic inflation that served as sites for the “condensation” of bright matter galaxies. We likely owe our existence to this stuff, whatever it is, which has yet to be directly detected. Along with dark energy, it remains one of the greatest mysteries of our age.
This Hubble image shows the distribution of dark matter in the center of the giant galaxy cluster Abell 1689, containing about 1,000 galaxies and trillions of stars. Researchers used the observed positions of 135 lensed images of 42 background galaxies to calculate the location and amount of dark matter in the cluster. They superimposed a map of these inferred dark matter concentrations, tinted blue, on an image of the cluster. The greastest concentration of dark matter is in the cluster’s center. Credit: NASA, ESA, D. Coe, N. Benitez , T. Broadhurst
As if that weren’t enough, dark matter comprises 85% of all the known matter reserves in the universe and 27% of the entire matter-energy cosmic budget. Ordinary stuff like stars, baseball bats and sushi constitute just 4.9% of the the total. The leading theory is that dark matter is “cold,” meaning it moves slowly compared to the speed of light, and it’s “dark” because it doesn’t produce or interact with light. The axion, a hypothetical elementary particle, appears to be good candidate for dark matter as do WIMPs or weakly interacting massive particles, but again, these exist only on paper.
According to calculations done in the 1990s and simulations performed in the last decade, dark matter forms “fine-grained streams” of particles that move at the same velocity and orbit galaxies such as ours. Streams can be much larger than our Solar System and criss-cross the galaxy. Prézeau compares the formation of fine-grained streams of dark matter to mixing chocolate and vanilla ice cream. Swirl a scoop of each together a few times and you get a mixed pattern, but you can still see the individual colors.
“When gravity interacts with the cold dark matter gas during galaxy formation, all particles within a stream continue traveling at the same velocity,” Prézeau said.
This illustration zooms in to show what dark matter hairs would look like around Earth. The hairs in this illustration are not to scale. Simulations show that the roots of such hairs can be 600,000 miles (1 million km) from Earth. Credit: NASA /JPL-Caltech
But a different scenario unfolds when a stream passes by an obstacle like the Earth or a moon. Prézeau used computer simulations to discover that when dark matter stream passes through a planet — dark matter passes right through us unlike ordinary matter — it’s focused into an ultra-dense filament or hair. Not a solo strand but a luxuriant crop bushy as a brewer’s beard.
According to Prézeau, hairs emerging from planets have both “roots,” the densest concentration of dark matter particles in the hair, and “tips,” where the hair ends. When particles of a dark matter stream pass through Earth’s core, they focus at the “root” of a hair, where the density of the particles is about a billion times more than average. The root of such a hair should be around 600,000 miles (1 million km) away from the surface, or a little more than twice as far as the moon. The stream particles that graze Earth’s surface will form the tip of the hair, about twice as far from Earth as the hair’s root.
The root of a dark matter hair produced from particles going through Jupiter’s core would be about 1 trillion times denser than average. Credit: NASA/JPL-Caltech
A stream passing through more massive Jupiter would have roots a trillion times denser than the original stream. Naturally, these dense concentrations would make ideal places to send a probe to study dark matter right here in the neighborhood.
The computer simulations reveal that changes in Earth’s density from inner core to outer core to mantle and crust are reflected in the shape of the hairs, showing up as “kinks” that correspond to transitions from one zone to the next. If it were possible to get our hands on this kind of information, we could use it to map to better map Earth’s interior and even the depth of oceans inside Jupiter’s moon Europa and Saturn’s Enceladus.
Earth getting its roots done. What’ll they think of next?
Planets and other objects in our Solar System. Credit: NASA.
First the quick facts: Our Solar System has eight “official” planets which orbit the Sun. Here are the planets listed in order of their distance from the Sun:
If you add in the dwarf planets, Ceres is located in the asteroid belt between Mars and Jupiter, while the remaining dwarf planets are in the outer Solar System and in order from the Sun are Pluto, Haumea, Makemake, and Eris. There is, as yet, a bit of indecision about the Trans-Neptunian Objects known as Orcus, Quaoar, 2007 O10, and Sedna and their inclusion in the dwarf planet category.
A mnemonic for this list would be “My Very Educated Mother Could Just Serve Us Noodles, Pie, Ham, Muffins, and Eggs” (and Steak, if Sedna is included.) You can find more tricks for remembering the order of the planets at our detailed article here.
Now, let’s look at a few details including the definition of a planet and a dwarf planet, as well as details about each of the planets in our Solar System.
Artistic impression of the Solar System, with all known terrestrial planets, as giants, and dwarf planets. Credit: NASA
What is a Planet?
In 2006, the International Astronomical Union (IAU) decided on the definition of a planet. The definition states that in our Solar System, a planet is a celestial body which:
is in orbit around the Sun,
has sufficient mass to assume hydrostatic equilibrium (a nearly round shape),
has “cleared the neighborhood” around its orbit.
is not a moon.
This means that Pluto, which was considered to be the farthest planet since its discovery in 1930, now is classified as a dwarf planet. The change in the definition came after the discovery three bodies that were all similar to Pluto in terms of size and orbit, (Quaoar in 2002, Sedna in 2003, and Eris in 2005).
With advances in equipment and techniques, astronomers knew that more objects like Pluto would very likely be discovered, and so the number of planets in our Solar System would start growing quickly. It soon became clear that either they all had to be called planets or Pluto and bodies like it would have to be reclassified.
With much controversy then and since, Pluto was reclassified as a dwarf planet in 2006. This also reclassified the asteroid Ceres as a dwarf planet, too, and so the first five recognized dwarf planets are Ceres, Pluto, Eris, Makemake and Haumea. Scientists believe there may be dozens more dwarf planets awaiting discovery.
Later, in 2008, the IAU announced the subcategory of dwarf planets with trans-Neptunian orbits would be known as “plutoids.” Said the IAU, “Plutoids are celestial bodies in orbit around the Sun at a distance greater than that of Neptune that have sufficient mass for their self-gravity to overcome rigid body forces so that they assume a hydrostatic equilibrium (near-spherical) shape, and that have not cleared the neighborhood around their orbit.”
This subcategory includes Ceres, Pluto, Haumea, Makemake, and Eris.
The Planets in our Solar System:
Having covered the basics of definition and classification, let’s get talking about those celestial bodies in our Solar System that are still classified as planets (sorry Pluto!). Here is a brief look at the eight planets in our Solar System. Included are quick facts and links so you can find out more about each planet.
Mercury: Mercury is the closest planet to our Sun, at just 58 million km (36 million miles) or 0.39 Astronomical Unit (AU) out. But despite its reputation for being sun-baked and molten, it is not the hottest planet in our Solar System (scroll down to find out who that dubious honor goes go!)
Mercury, as imaged by the MESSENGER spacecraft, revealing parts of the never seen by human eyes. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington
Mercury is also the smallest planet in our Solar System, and is also smaller than its largest moon (Ganymede, which orbits Jupiter). And being equivalent in size to 0.38 Earths, it is just slightly larger than the Earth’s own Moon. But this may have something to do with its incredible density, being composed primarily of rock and iron ore. Here are the planetary facts:
Diameter: 4,879 km (3,032 miles)
Mass: 3.3011 x 1023 kg (0.055 Earths)
Length of Year (Orbit): 87.97 Earth days
Length of Day: 59 Earth days.
Mercury is a rocky planet, one of the four “terrestrial planets” in our Solar System. Mercury has a solid, cratered surface, and looks much like Earth’s moon.
If you weigh 45 kg (100 pounds) on Earth, you would weigh 17 kg (38 pounds) on Mercury.
Mercury does not have any moons.
Temperatures on Mercury range between -173 to 427 degrees Celcius (-279 to 801 degrees Fahrenheit)
Just two spacecraft have visited Mercury: Mariner 10 in 1974-75 and MESSENGER, which flew past Mercury three times before going into orbit around Mercury in 2011 and ended its mission by impacting the surface of Mercury on April 30, 2015. MESSENGER has changed our understanding of this planet, and scientists are still studying the data.
Venus:
Venus is the second closest planet to our Sun, orbiting at an average distance of 108 million km (67 million miles) or 0.72 AU. Venus is often called Earth’s “sister planet,” as it is just a little smaller than Earth. Venus is 81.5% as massive as Earth, and has 90% of its surface area and 86.6% of its volume. The surface gravity, which is 8.87 m/s², is equivalent to 0.904 g – roughly 90% of the Earth standard.
A radar view of Venus taken by the Magellan spacecraft, with some gaps filled in by the Pioneer Venus orbiter. Credit: NASA/JPL
And due to its thick atmosphere and proximity to the Sun, it is the Solar Systems hottest planet, with temperatures reaching up to a scorching 735 K (462 °C). To put that in perspective, that’s over four and a half times the amount of heat needed to evaporate water, and about twice as much needed to turn tin into molten metal (231.9 °C)!
Diameter: 7,521 miles (12,104 km)
Mass: 4.867 x 1024 kg (0.815 Earth mass)
Length of Year (Orbit): 225 days
Length of day: 243 Earth days
Surface temperature: 462 degrees C (864 degrees F)
Venus’ thick and toxic atmosphere is made up mostly of carbon dioxide (CO2) and nitrogen (N2), with clouds of sulfuric acid (H2SO4) droplets.
Venus has no moons.
Venus spins backwards (retrograde rotation), compared to the other planets. This means that the sun rises in the west and sets in the east on Venus.
If you weigh 45 kg (100 pounds) on Earth, you would weigh 41 kg (91 pounds) on Venus.
Venus is also known and the “morning star” or “evening star” because it is often brighter than any other object in the sky and is usually seen either at dawn or at dusk. Since it is so bright, it has often been mistaken for a UFO!
More than 40 spacecraft have explored Venus. The Magellan mission in the early 1990s mapped 98 percent of the planet’s surface. Find out more about all the missions here.
Earth: Our home, and the only planet in our Solar System (that we know of) that actively supports life. Our planet is the third from the our Sun, orbiting it at an average distance of 150 million km (93 million miles) from the Sun, or one AU. Given the fact that Earth is where we originated, and has all the necessary prerequisites for supporting life, it should come as no surprise that it is the metric on which all others planets are judged.
Earth, pictured by the crew of the Apollo 17 mission. Credit: NASA
Whether it is gravity (g), distance (measured in AUs), diameter, mass, density or volume, the units are either expressed in terms of Earth’s own values (with Earth having a value of 1) or in terms of equivalencies – i.e. 0.89 times the size of Earth. Here’s a rundown of the kinds of
Diameter: 12,760 km (7,926 miles)
Mass: 5.97 x 1024 kg
Length of Year (Orbit): 365 days
Length of day: 24 hours (more precisely, 23 hours, 56 minutes and 4 seconds.)
Surface temperature: Average is about 14 C, (57 F), with ranges from -88 to 58 (min/max) C (-126 to 136 F).
Earth is another terrestrial planet with an ever-changing surface, and 70 percent of the Earth’s surface is covered in oceans.
Earth has one moon.
Earth’s atmosphere is 78% nitrogen, 21% oxygen, and 1% various other gases.
Mars: Mars is the fourth planet from the sun at a distance of about 228 million km (142 million miles) or 1.52 AU. It is also known as “the Red Planet” because of its reddish hue, which is due to the prevalence of iron oxide on its surface. In many ways, Mars is similar to Earth, which can be seen from its similar rotational period and tilt, which in turn produce seasonal cycles that are comparable to our own.
Global image of the planet Mars. Credit: NASA
The same holds true for surface features. Like Earth, Mars has many familiar surface features, which include volcanoes, valleys, deserts, and polar ice caps. But beyond these, Mars and Earth have little in common. The Martian atmosphere is too thin and the planet too far from our Sun to sustain warm temperatures, which average 210 K (-63 ºC) and fluctuate considerably.
Diameter: 6,787 km, (4,217 miles)
Mass: 6.4171 x 1023 kg (0.107 Earths)
Length of Year (Orbit): 687 Earth days.
Length of day: 24 hours 37 minutes.
Surface temperature: Average is about -55 C (-67 F), with ranges of -153 to +20 °C (-225 to +70 °F)
Mars is the fourth terrestrial planet in our Solar System. Its rocky surface has been altered by volcanoes, impacts, and atmospheric effects such as dust storms.
Mars has a thin atmosphere made up mostly of carbon dioxide (CO2), nitrogen (N2) and argon (Ar).If you weigh 45 kg (100 pounds) on Earth, you would weigh 17 kg (38 pounds) on Mars.
Mars has two small moons, Phobos and Deimos.
Mars is known as the Red Planet because iron minerals in the Martian soil oxidize, or rust, causing the soil to look red.
Jupiter: Jupiter is the fifth planet from the Sun, at a distance of about 778 million km (484 million miles) or 5.2 AU. Jupiter is also the most massive planet in our Solar System, being 317 times the mass of Earth, and two and half times larger than all the other planets combined. It is a gas giant, meaning that it is primarily composed of hydrogen and helium, with swirling clouds and other trace gases.
Io and Jupiter as seen by New Horizons during its 2008 flyby. (Credit: NASA/Johns Hopkins University APL/SWRI).
Jupiter’s atmosphere is the most intense in the Solar System. In fact, the combination of incredibly high pressure and coriolis forces produces the most violent storms ever witnessed. Wind speeds of 100 m/s (360 km/h) are common and can reach as high as 620 km/h (385 mph). In addition, Jupiter experiences auroras that are both more intense than Earth’s, and which never stop.
Diameter: 428,400 km (88,730 miles)
Mass: 1.8986 × 1027 kg (317.8 Earths)
Length of Year (Orbit): 11.9 Earth years
Length of day: 9.8 Earth hours
Temperature: -148 C, (-234 F)
Jupiter has 67 known moons, with an additional 17 moons awaiting confirmation of their discovery – for a total of 67 moons. Jupiter is almost like a mini solar system!
Jupiter has a faint ring system, discovered in 1979 by the Voyager 1 mission.
If you weigh 45 kg (100 pounds) on Earth, you would weigh 115 kg (253) pounds on Jupiter.
Jupiter’s Great Red Spot is a gigantic storm (bigger than Earth) that has been raging for hundreds of years. However, it appears to be shrinking in recent years.
Many missions have visited Jupiter and its system of moons, with the latest being the Juno mission will arrive at Jupiter in 2016. You can find out more about missions to Jupiter here.
Saturn’s relatively thin main rings are about 250,000 km (156,000 miles) in diameter. (Image: NASA/JPL-Caltech/SSI/J. Major)
Saturn: Saturn is the sixth planet from the Sun at a distance of about 1.4 billion km (886 million miles) or 9.5 AU. Like Jupiter, it is a gas giant, with layers of gaseous material surrounding a solid core. Saturn is most famous and most easily recognized for its spectacular ring system, which is made of seven rings with several gaps and divisions between them.
Diameter: 120,500 km (74,900 miles)
Mass: 5.6836 x 1026 kg (95.159 Earths)
Length of Year (Orbit): 29.5 Earth years
Length of day: 10.7 Earth hours
Temperature: -178 C (-288 F)
Saturn’s atmosphere is made up mostly of hydrogen (H2) and helium (He).
If you weigh 45 kg (100 pounds) on Earth, you would weigh about 48 kg (107 pounds) on Saturn
Saturn has 53 known moons with an additional 9 moons awaiting confirmation.
Five missions have gone to Saturn. Since 2004, Cassini has been exploring Saturn, its moons and rings. You can out more about missions to Saturn here.
Uranus: Uranus is the seventh planet from the sun at a distance of about 2.9 billion km (1.8 billion miles) or 19.19 AU. Though it is classified as a “gas giant”, it is often referred to as an “ice giant” as well, owing to the presence of ammonia, methane, water and hydrocarbons in ice form. The presence of methane ice is also what gives it its bluish appearance.
Uranus as seen by NASA’s Voyager 2 space probe. Credit: NASA/JPL
Uranus is also the coldest planet in our Solar System, making the term “ice” seem very appropriate! What’s more, its system of moons experience a very odd seasonal cycle, owing to the fact that they orbit Neptune’s equator, and Neptune orbits with its north pole facing directly towards the Sun. This causes all of its moons to experience 42 year periods of day and night.
Diameter: 51,120 km (31,763 miles)
Mass:
Length of Year (Orbit): 84 Earth years
Length of day: 18 Earth hours
Temperature: -216 C (-357 F)
Most of the planet’s mass is made up of a hot dense fluid of “icy” materials – water (H2O), methane (CH4). and ammonia (NH3) – above a small rocky core.
Uranus has an atmosphere which is mostly made up of hydrogen (H2) and helium (He), with a small amount of methane (CH4). The methane gives Uranus a blue-green tint.
If you weigh 45 kg (100 pounds) on Earth, you would weigh 41 kg (91 pounds) on Uranus.
Uranus has 27 moons.
Uranus has faint rings; the inner rings are narrow and dark and the outer rings are brightly colored.
Voyager 2 is the only spacecraft to have visited Uranus. Find out more about this mission here.
Neptune: Neptune is the eighth and farthest planet from the Sun, at a distance of about 4.5 billion km (2.8 billion miles) or 30.07 AU. Like Jupiter, Saturn and Uranus, it is technically a gas giant, though it is more properly classified as an “ice giant” with Uranus.
Neptune photographed by the Voyager 2 space probe. Credit: NASA/JPL
Due to its extreme distance from our Sun, Neptune cannot be seen with the naked eye, and only one mission has ever flown close enough to get detailed images of it. Nevertheless, what we know about it indicates that it is similar in many respects to Uranus, consisting of gases, ices, methane ice (which gives its color), and has a series of moons and faint rings.
Diameter: 49,530 km (30,775 miles)
Mass: 1.0243 x 1026 kg (17 Earths)
Length of Year (Orbit): 165 Earth years
Length of day: 16 Earth hours
Temperature: -214 C (-353 F)
Neptune is mostly made of a very thick, very hot combination of water (H2O), ammonia (NH3), and methane (CH4) over a possible heavier, approximately Earth-sized, solid core.
Neptune’s atmosphere is made up mostly of hydrogen (H2), helium (He) and methane (CH4).
Neptune has 13 confirmed moons and 1 more awaiting official confirmation.
Neptune has six rings.
If you weigh 45 kg (100 pounds) on Earth, you would weigh 52 kg (114 pounds) on Neptune.
Neptune was the first planet to be predicted to exist by using math.
Voyager 2 is the only spacecraft to have visited Neptune. You can find out more about this mission here.
Find out more about Neptune at this series of articles on Universe Today and this NASA webpage. We have written many articles about the planets for Universe Today. Here are some facts about planets, and here’s an article about the names of the planets.If you’d like more info on the Solar System planets, dwarf planets, asteroids and more, check out NASA’s Solar System exploration page, and here’s a link to NASA’s Solar System Simulator.We’ve also recorded a series of episodes of Astronomy Cast about every planet in the Solar System. Start here, Episode 49: Mercury.Venus is the second planet from the Sun, and it is the hottest planet in the Solar System due to its thick, toxic atmosphere which has been described as having a “runaway greenhouse effect” on the planet.
Now you know! And if you find yourself unable to remember all the planets in their proper order, just repeat the words, “My Very Educated Mother Just Served Us Noodles.” Of course, the Pie, Ham, Muffins and Eggs are optional, as are any additional courses that might be added in the coming years!
Astronomers hate the Moon because it ruins perfectly good observing nights. But is it possible that we all need the Moon for our very existence?
For all we know, Earth is the only place in the Universe where life appeared. This makes the mystery of our existence even more puzzling. What were all the factors required to bring about the first lifeforms on our planet, and encourage the evolution of more complex, intelligent lifeforms.
We needed a calm and reasonable Sun, solid ground, nice temperatures, the appropriate chemicals, and liquid water. Possibly drinks served in pineapples with little umbrellas. But what about the Moon? Is the Moon a necessity for life in any way?
To the best of our knowledge, our Moon was formed when a Mars-sized object smashed into the Earth about 4.5 billion years ago. This enormous collision spun out a cloud of debris that coalesced into the Moon we know and love today.
Back then, the Moon was much closer to the Earth than it is today, a mere 20-30,000 kilometers. A fraction of its current distance. If you could have stood on the surface of the Earth, the Moon would have looked 10 to 20 times bigger than we see it today.
But nobody did, because the Earth was a molten ball of red hot magma, tasty lava through and through. Life emerged 3.8 billion years ago, pretty much the day after Earth had cooled down to the point that it was possible for life to form.
Scientists think that it first formed in the oceans, where there were adequate temperatures and abundant water as a solvent for life’s chemicals to mix.
The effect of gravity is a cube of its distance. When the Moon was closer, the power of its gravity to pull the Earth’s water around was more ferocious. But what impact has this gravity had on our world and its life? Do we need the Moon to make the magic happen?
Turns out, we might owe our very existence to it because its pull of gravity might have set our plate tectonics in motion. Without plate tectonics, our planet might be more like Venus, toasty and dead.
Map of the Earth showing fault lines (blue) and zones of volcanic activity (red). Credit: zmescience.com
It raises the level of the world’s oceans towards the equator. Without this gravity, the oceans would redistribute, raising levels at the poles. It has also slowed Earth’s rotation on its axis. Shortly after its formation, the Earth turned once every 6 hours. Without that Moon to slow us down, we’d have much more severe weather.
It stabilizes the Earth’s rotation on its axis. It’s possible that the Earth might have rolled over on its axis on a regular basis, causing a complete redistribution of the Earth’s water. Astronomers think this happened on Mars, because it never had a large Moon to stabilize it.
But the biggest impact that the Moon has on life is through tides. That regular movement of water that exposes the land at the edge of the ocean, and then covers it again just a few hours later. This could have encouraged life to adapt and move from the oceans to land.
One of the most subtle effects from the Moon is what it has done to life itself. Nocturnal animals behave differently depending on where the Moon is in the sky during its 29.5-day cycle. When the Moon is full and bright, prey fish stay hidden in the reef, when they’d be most visible.
Prey fish in the reef. Credit: Laslo Ilyes
Amazingly, lions are less likely to hunt during the full Moon, and researchers have found that lion attacks on humans happen 10 days after the full Moon, and many bats will be less active during the full Moon.
With so many species on Earth affected by the Moon, it’s reasonable to think that there would have been a different evolutionary direction for life on Earth over the eons, and humans might never have evolved.
It looks like the Moon is important after all. Important to the geology of Earth, and important to the evolution of life itself.
As extrasolar planet hunters search for new worlds, and determine their viability for life, they might want to focus on the worlds with moons first.
What impact has the Moon had on your life? Post your anecdotes in the comments!
The International Space Station (ISS) has grown tremendously in size and complexity and evolved significantly over 15 years of continuous human occupation from Nov. 2, 2000 to Nov. 2, 2015. Credit: NASA
The International Space Station (ISS) achieved 15 years of a continuous human presence in orbit, as of today, Nov. 2, aboard the football field sized research laboratory ever since the first Russian/American crew of three cosmonauts and astronauts comprising Expedition 1 arrived in a Soyuz capsule at the then much tinier infant orbiting complex on Nov. 2, 2000.
Today, the space station is host to the Expedition 45 crew of six humans – from America, Russia and Japan – that very symbolically also includes the first ever crew spending one year aboard and that highlights the outposts expanding role from a research lab to a deep space exploration test bed for experiments and technologies required for sending humans on interplanetary journeys to the Martian system in the 2030s.
The ISS was only made possible by over two decades of peaceful and friendly international cooperation by the most powerful nations on Earth on a scale rarely seen.
“I believe the International Space Station should be considered for the Nobel Peace Prize,” said NASA Administrator Charles Bolden last week during remarks to the Center for American Progress in Washington, DC., on October 28, 2015.
“Exploration has taught us more than we have ever known about our Universe and our place in it.”
“The ISS has already taught us what’s possible when tens of thousands of people across 15 countries collaborate so that human beings from different nations can live and work in space together.”
“Yet, for all these accomplishments, when you consider all the possibilities ahead of us you can only reach one conclusion; We are just getting started!”
6 person ISS Expedition 45 Crew celebrates 15 Years of operation with humans on 2 Nov 2015. Credit: NASA
“No better place to celebrate #15YearsOnStation! #HappyBday, @space_station! Thanks for the hospitality! #YearInSpace.” tweeted NASA astronaut Scott Kelly from the ISS today along with a crew portrait.
The space station is the largest engineering and construction project in space combining the funding, hardware, knowhow, talents and crews from 5 space agencies and 15 countries – NASA, Roscomos, ESA (European Space Agency), JAXA (Japan Aerospace and Exploration Agency) and CSA (Canadian Space Agency).
NASA astronaut Tracy Caldwell Dyson, an Expedition 24 flight engineer in 2010, took a moment during her space station mission to enjoy an unmatched view of home through a window in the Cupola of the International Space Station, the brilliant blue and white part of Earth glowing against the blackness of space. Credits: NASA
The collaborative work in space has transcended our differences here on Earth and points the way forward to an optimistic future that benefits all humanity.
The station orbits at an altitude of about 250 miles (400 kilometers) above Earth. It measures 357 feet (109 meters) end-to-end and has an internal pressurized volume of 32,333 cubic feet, equivalent to that of a Boeing 747.
The uninterrupted human presence on the station all began when Expedition 1 docked at the outpost on Nov. 2, 2000, with its first residents including Commander William Shepherd of NASA and cosmonauts Sergei Krikalev and Yuri Gidzenko of Roscosmos.
For the first station trio in November 2000, the vehicle included three modules; the Zarya module and the Zvezda service module from Russia and the Unity module from the US.
In this photo, Expedition 1 crew members (from left to right) Commander Bill Shepherd, and Flight Engineers Yuri Gidzenko and Sergei Krikalev pose with a model of their home away from home. Image Credit: NASA
Over the past 15 years, after more than 115 construction and logistics flight, the station has grown by leaps and bounds from its small initial configuration of only three pressurized modules from Russian and America into a sprawling million pound orbiting outpost sporting a habitable volume the size of a six bedroom house, with additional new modules and hardware from Europe, Japan and Canada.
The ISS has been visited by over 220 people from 17 countries.
The “1 Year ISS crew” reflects the international cooperation that made the station possible and comprises current ISS commander NASA astronaut Scott Kelly and Russian cosmonaut Mikhail Kornienko, who are now just past the half way mark of their mission.
“Over the weekend, I called NASA astronaut Scott Kelly, who is currently halfway through his one-year mission aboard the International Space Station, to congratulate him on setting the American records for both cumulative and continuous days in space,” Bolden said in a NASA statement released today.
“I also took the opportunity to congratulate Commander Kelly — and the rest of the space station crew — for being part of a remarkable moment 5,478 days in the making: the 15th anniversary of continuous human presence aboard the space station.”
Scott Kelly, U.S. astronaut and commander of the current Expedition 45 crew, broke the US record for time spent in space on Oct. 16, 2015. Credit: NASA
The complete Expedition 45 crew members include Station Commander Scott Kelly and Flight Engineer Kjell Lindgren of NASA, Flight Engineers Mikhail Kornienko, Oleg Kononenko and Sergey Volkov of the Russian Federal Space Agency (Roscosmos) and Flight Engineer Kimiya Yui of the Japan Aerospace Exploration Agency.
For the first nine years, the station was home to crews of two or three. Starting in 2009 the crew size was doubled to a permanent crew of six humans after the habitable volume, research facilities, equipment and supporting provisions had grown sufficiently.
“Humans have been living in space aboard the International Space Station 24-7-365 since Nov. 2, 2000. That’s 15 Thanksgivings, New Years, and holiday seasons astronauts have spent away from their families. 15 years of constant support from Mission Control Houston. And 15 years of peaceful international living in space,” says NASA.
Expedition 45 Crew Portrait: Station Commander Scott Kelly and Flight Engineer Kjell Lindgren of NASA, Flight Engineers Mikhail Kornienko, Oleg Kononenko and Sergey Volkov of the Russian Federal Space Agency (Roscosmos) and Flight Engineer Kimiya Yui of the Japan Aerospace Exploration Agency. Credit: NASA/Roscosmos/JAXA
The US contributed and built the largest number of segments of the space station, followed by Russia.
NASA’s Space Shuttles hauled the US segments aloft inside the orbiters huge payload bay, starting from the first construction mission in 1998 carrying the Unity module to the final shuttle flight STS-135 in 2011, which marked the completion of construction and retirement of the shuttles.
With the shuttle orbiters now sitting in museums and no longer flying, the Russian Soyuz capsule is the only means of transporting crews to the space station and back.
The longevity of the ISS was recently extended from 2020 to 2024 after approval from President Obama. Most of the partners nations have also agreed to the extension. Many in the space community believe the station hardware is quite resilient and hope for further extensions to 2028 and beyond.
“The International Space Station, which President Obama has extended through 2024, is a testament to the ingenuity and boundless imagination of the human spirit. The work being done on board is an essential part of NASA’s journey to Mars, which will bring American astronauts to the Red Planet in the 2030s,” says Bolden.
“For 15 years, humanity’s reach has extended beyond Earth’s atmosphere. Since 2000, human beings have been living continuously aboard the space station, where they have been working off-the-Earth for the benefit of Earth, advancing scientific knowledge, demonstrating new technologies, and making research breakthroughs that will enable long-duration human and robotic exploration into deep space.”
A key part of enabling long duration space missions to Mars is the 1 Year ISS Mission.
In coming years, additional new pressurized modules and science labs will be added by Russia and the US.
And NASA says the stations crew size will expand to seven after the US commercial Starliner and Dragon space taxis from Boeing and SpaceX start flying in 2017.
NASA is now developing the new Orion crew capsule and mammoth Space Launch System (SLS) heavy lift rocket to send astronauts to deep space destination including the Moon, asteroids and the Red Planet.
In the meantime, Kelly and his crew are also surely looking forward to the arrival of the next Orbital ATKCygnus resupply ship carrying science experiments, provisions, spare parts, food and other goodies after it blasts off from Florida on Dec. 3 – detailed in my story here.
Infographic: 15 Years of Continuous Human Presence Aboard the International Space Station. Credit: NASA
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
STS-135: Last launch using RS-25 engines that will now power NASA’s SLS deep space exploration rocket. NASA’s 135th and final shuttle mission takes flight on July 8, 2011 at 11:29 a.m. from the Kennedy Space Center in Florida bound for the final flight to the ISS and the high frontier with Chris Ferguson as Space Shuttle Commander. Credit: Ken Kremer/kenkremer.com
“Hurricane #Patricia approaches #Mexico. It's massive. Be careful” in this image taken by NASA astronaut Scott Kelly aboard the ISS on Oct. 23, 2015. Credit: NASA/Scott Kelly
“Hurricane #Patricia approaches #Mexico. It’s massive. Be careful” in this image taken by NASA astronaut Scott Kelly aboard the ISS on Oct. 23, 2015. Credit: NASA/Scott Kelly
More images and videos below[/caption]
Hurricane Patricia, the strongest storm in recorded history with winds exceeding 190 mph (305 km/h) is right now menacing millions in Mexico after suddenly intensifying with little warning over the past day, threatening widespread catastrophic destruction as it barrels towards frightened residents along the nations Pacific coast and makes landfall this evening, Friday, Oct. 23.
Other NASA and NOAA weather satellites are actively monitoring and measuring the strongest storm on the planet right now.
“Hurricane #Patricia approaches #Mexico. It’s massive. Be careful,” Kelly wrote on his twitter account with a pair of images taken from the ISS.
Patricia unexpectedly intensified quite rapidly to a Category 5 storm from a tropical storm in the space of just 24 hours from yesterday to today with the significant potential for loss of life and likely widespread catastrophic damage.
This morning Patricia had sustained winds of 190 mph (305 km/h) , on the Saffir-Simpson Hurricane Wind Scale, with gusts up to 235 mph. That’s comparable to an EF-4 tornado, but its much wider.
Weather forecasters say that unusually warm waters, possibly from the current El Niño weather pattern may be causing the rapid intensification of the storm to unprecedented power never before seen.
On Oct. 23 at 17:30 UTC (1:30 p.m. EDT) NASA’s Terra satellite saw the eastern quadrant of Hurricane Patricia over Mexico and the storm’s pinhole eye. Credits: NASA’s Goddard MODIS Rapid Response Team
“Hurricane #Patricia looks menacing from @space_station. Stay safe below,” tweeted Kelly, who just broke the American record for most time spent in space.
Patricia is making landfall near the tourist resort of Puerto Vallarta, the town of Cuixmala and the city of Manzanillo along Mexico’s Pacific coast, as it slightly weakens to 165 mph (265 km/h) with destructive force.
Here is the latest Hurricane Patricia animation from NOAA:
Patricia is the most powerful storm ever to make landfall and many millions live in its path that is expected to track eastwards across inland areas of Mexico and then move up into the United States at Texas with flooding rains.
The Mexican government has warned millions to take shelter to evacuate. Over 15000 tourists have been evacuated from Puerto Vallarta to other regions. But the effort was hampered since the airport has been closed.
Catastrophic destruction to homes, businesses and infrastructure is feared.
Some 10 to 20 inches of rain is expected along the coast, causing mudslides across Mexico.
Waves heights exceeding 30 feet are also expected.
Heavy rains and flash flooding will continue into the US with the heaviest downpours expected in Texas and Louisiana.
Hurricane Patricia on Oct. 23, 2015 from the National Hurricane Center
Here’s the 7 PM CDT advisory from the National Hurricane Center:
“EXTREMELY DANGEROUS HURRICANE PATRICIA MOVING FARTHER INLAND OVER SOUTHWESTERN MEXICO”
“The center of Hurricane Patricia was located near latitude 19.5 North, longitude 104.9 West. Patricia ismoving toward the north-northeast near 15 mph (24 km/h) and this motion is expected to continue with some increase in forward speed tonight and Saturday. On the forecast track, the center of Patricia should continue to move inland over southwestern Mexico.
Patricia is expected to move quickly north-northeastward across western and northern Mexico through Saturday.
Satellite images indicate that Patricia has continued to weaken, and maximum sustained winds are estimated to be near 160 mph (260 km/h) with higher gusts. Patricia is a category 5 hurricane on the Saffir-Simpson Hurricane Wind Scale. Patricia is forecast to rapidly weaken over the mountains of Mexico and dissipate on Saturday.
Hurricane force winds extend outward up to 35 miles (55 km) from the center and tropical storm force winds extend outward up to 175 miles (280 km).
The estimated minimum central pressure is 924 mb (27.29 inches).”
Here’s a video of Hurricane Patricia from the ISS taken today, Oct 23, 2015.
Video caption: Outside the International Space Station, cameras captured dramatic views of Hurricane Patricia at 12:15 p.m. EDT on October 23, 2015 as the mammoth system moved north at about 10 mph, heading for a potentially catastrophic landfall along the southwest coast of Mexico sometime during the day, according to the National Hurricane Center. Packing winds of 200 miles per hour, Patricia is the strongest in recorded history in the southeastern Pacific Ocean. The National Hurricane Center says that once Patricia crosses the Mexican coast it should weaken quickly and dissipate Oct. 24 due to upper level winds and mountainous terrain, but likely will introduce copious amounts of rainfall to the Texas coast through the weekend. Credit: NASA
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
Earth rotates through an entire day as captured in this animation of 22 still images taken on Sept. 17, 2015 by NASA’s Earth Polychromatic Imaging Camera (EPIC) camera on the Deep Space Climate Observatory (DSCOVR) spacecraft. Credits: NASA
The EPIC camera, which stands for Earth Polychromatic Imaging Camera (EPIC), is located a million miles away on the DSCOVR real time space weather monitoring satellite and is designed to take full disk color images of the sunlit side of our home planet multiple times per day.
The EPIC NASA images are literally just a finger tip away, after a 17 year wait to get the satellite into the launch queue since it was first proposed by former VP Al Gore. They are all easily viewed at NASA’s new EPIC camera website which went online today, Monday, October 19, 2015.
This EPIC image was taken on Oct.17 and shows the Australian continent and a portion of Asia.
EPIC image taken on Oct. 17, 2015 showing the continent of Australia and a portion of Asia. Credit: NASA
An annotated guide map illustration identifying the visible land masses accompanies each EPIC image and follows along as the Earth rotates daily.
What a great geography learning tool for student classrooms worldwide!
Annotated guide map identifying the visible land masses accompanies each EPIC image. Credit: NASA
DSCOVR is a joint mission between NOAA, NASA, and the U.S Air Force (USAF) that is managed by NOAA. The satellite and science instruments were provided by NASA and NOAA.
EPIC is a four megapixel CCD camera and telescope mounted on DSCOVR and orbiting around the L1 Lagrange Point – a neutral gravity point that lies on the direct line between Earth and the sun.
NASA says that once per day they will post “at least a dozen new color images of Earth acquired from 12 to 36 hours earlier” taken by the agency’s EPIC camera. The EPIC images will be stored in an archive searchable by date and continent.
The image sequence will show “the Earth as it rotates, thus revealing the whole globe over the course of a day.”
“The effective resolution of the DSCOVR EPIC camera is somewhere between 6.2 and 9.4 miles (10 and 15 kilometers),” said Adam Szabo, DSCOVR project scientist at NASA’s Goddard Space Flight Center, Greenbelt, Maryland, in a statement.
“The color Earth images are created by combining three separate single-color images to create a photographic-quality image equivalent to a 12-megapixel camera. The camera takes a series of 10 images using different narrowband filters — from ultraviolet to near infrared — to produce a variety of science products. The red, green and blue channel images are used to create the color images. Each image is about 3 megabytes in size.”
EPIC will capture “a constant view of the fully illuminated Earth as it rotates, providing scientific observations of ozone, vegetation, cloud height and aerosols in the atmosphere.”
Technician works on NASA Earth science instruments and Earth imaging EPIC camera (white circle) housed on NOAA/NASA Deep Space Climate Observatory (DSCOVR) inside NASA Goddard Space Flight Center clean room in November 2014. Credit: Ken Kremer/kenkremer.com
The couch sized probe was launched atop a SpaceX Falcon 9 on Feb. 11, 2015 from Cape Canaveral, Florida, to start the million mile journey to its deep space observation post at L1. The rocket was funded by the USAF.
The primary goal of the $340 million DSCOVR satellite is to monitor the solar wind and aid very important forecasts of space weather at Earth from L1.
L1 is located 1.5 million kilometers (932,000 miles) sunward from Earth. At L1 the gravity between the sun and Earth is perfectly balanced and the DSCOVR satellite orbits about that spot just like a planet.
The mission is vital because its solar wind observations are crucial to maintaining accurate space weather forecasts to protect US infrastructure such as power grids, aviation, planes in flight, all types of Earth orbiting satellites for civilian and military needs, telecommunications, ISS astronauts and GPS systems.
This animation shows images of the far side of the moon, illuminated by the sun, as it crosses between the DISCOVR spacecraft’s Earth Polychromatic Imaging Camera (EPIC) camera and telescope, and the Earth – one million miles away. Credit: NASA/NOAA
DSCOVR was first proposed in 1998 by then US Vice President Al Gore as the low cost ‘Triana’ satellite to take near continuous views of the Earth’s entire globe to feed to the internet as a means of motivating students to study math and science.
It was also dubbed “Goresat.”
The probe was eventually resurrected and partially rebuilt at NASA Goddard Space Flight Center as a much more capable Earth science satellite that would also conduct the space weather observations.
But Triana was shelved for purely partisan political reasons and the satellite was placed into storage at NASA Goddard.
Thus the practical and teachable science and daily scenes of the gorgeously rotating Earth were lost – until now!
Former VP Al Gore was clearly delighted with today’s launch of NASA’s EPIC website in this pair of tweets:
“Today @NASA launched its site for #DSCOVR’s daily images. I look forward to seeing more from #DSCOVR,” tweeted Al Gore.
“DSCOVR’s site displaying new daily images of Earth from L1 was launched today! Congratulations to all those who made this happen!”
Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.
NOAA/NASA Deep Space Climate Observatory (DSCOVR) undergoes processing in NASA Goddard Space Flight Center clean room. Solar wind instruments at right. DSCOVER launched in February 2015 atop SpaceX Falcon 9 rocket. Credit: Ken Kremer/kenkremer.com
NOAA/NASA/USAF Deep Space Climate Observatory (DSCOVR) undergoes processing in NASA Goddard Space Flight Center clean room. Probe launched in February 2015 atop SpaceX Falcon 9 rocket. Credit: Ken Kremer/kenkremer.com
Like me, you’re probably a little ego-geocentric about the importance of Earth. It’s where you were born, it’s where you keep all your stuff. It’s even where you’re going to die – I know, I know, not you Elon Musk, you’re going to “retire” on Mars, right after you nuke the snot out of it.
For the rest of us, Earth is the place. But in reality, when it comes to planets, this is somebody else’s racket. This is Jupiter’s Solar System, and we all sleep on its couch.
Jupiter accounts for 75% of the mass of the planets of the Solar System, nearly 318 times more massive than Earth, and isn’t just the name of everyone’s favorite secret princess. It’s the 1.9 × 10^27 kilogram gorilla in the room. Whatever Jupiter wants, Jupiter gets. Jupiter hungry? JUPITER HUNGRY.
What Jupiter apparently wants is to throw our stuff around the Solar System. Thanks to its immense gravity, Jupiter yanks material around in the asteroid belt, preventing the poor space rocks from ever forming up into anything larger than Ceres.
Jupiter gobbles up asteroids, comets, and spacecraft, and hurtles others on wayward trajectories. Who knows how much mayhem and destruction Jupiter has gotten into over the course of its 4.5 billion years in the Solar System.
Some scientists think we owe our existence to Jupiter’s protective gravity. It greedily vacuums up dangerous asteroids and comets in the Solar System.
Other scientists totally disagree and think that Jupiter is a bully, perturbing perfectly safe comets and asteroids into dangerous trajectories and flushing earth’s head in the toilet during recess.
Which is it? Is Jupiter our friend and protector, or evil enemy. We’ve already figured out how to dismantle you Jupiter, don’t make us put our plans into action.
Some of the most dangerous objects in the Solar System are long-period comets. These balls of rock and ice come from the deepest depths of the Oort cloud. Some event nudges these death missiles into trajectories that bring them into the inner Solar System, to shoot past the Sun and maybe, just maybe, smash into a planet and kill 99.99999% of the life on it.
The Solar System. Credit: NASA
There’s a pretty good chance some of the biggest extinctions in the history of the Earth were caused by impacts by long period comets.
As these comets make their way through the Solar System, they interact with Jupiter’s massive gravity, and get pushed this way and that. As we saw with Comet Shoemaker-Levy, some just get consumed entirely, like a tasty ice-rock sandwich.
The theory goes that Jupiter pushes these dangerous comets out of their murder orbits so they don’t smash into Earth and kill us all.
But a competing theory says that Jupiter actually diverts comets that would have completely missed our planet into deadly, Earth-killing trajectories.
Will the Sailor Scouts provide us any clues? Who can say?
At top, an image of the comet Shoemaker-Levy 9 (May 1994) after a close approach with Jupiter which tore the comet into numerous fragments. An image taken by Andrew Catsaitis of components B and C of Comet 73P/Schwassmann–Wachmann 3 as seen together on 31 May 2006 (Credit: NASA/HST, Wikipedia, A.Catsaitis)
Here’s friend of the show, Dr. Kevin Grazier, a planetary scientist and scientific advisor for many of your favorite sci-fi TV shows and movies.
… [ see video for Interview with Dr. Grazier about Jupiter]
So which is it? Is Jupiter our friend or enemy? We’ll need to run more simulations and figure this out with more accuracy. And until then, it’s probably best if we just tremble in fear and worship Jupiter as a dark and capricious god until the evidence proves otherwise. It’s what Pascal would wager.
What are some other theories you’ve heard about and you’d like us to dig in further? Make some suggestions in the comments below.
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![Space Shuttle Endeavour sillouetted against the atmosphere. The orange layer is the troposphere, the white layer is the stratosphere and the blue layer the mesosphere.[1] (The shuttle is actually orbiting at an altitude of more than 320 km (200 mi), far above all three layers.) Credit: NASA](https://www.universetoday.com/wp-content/uploads/2012/03/Endeavour_silhouette_STS-130.jpg)
