Mars Archives

April 27, 2014December 23, 2015 by Ken Kremer

Curiosity Reaches Out to Scrutinize Next Martian Drill Target at Mount Remarkable

Multisol composite photo mosaic shows deployment of Curiosity’s rovers robotic arm and APXS X-ray spectrometer onto the ‘Winjana’ rock target at Mount Remarkable for evaluation as missions third drill target inside Gale Crater on Mars. The colorized navcam raw images were stitched together from several Martian days up to Sol 612, April 26, 2014. Credit: NASA/JPL-Caltech/Ken Kremer - kenkremer.com/Marco Di Lorenzo

Multisol composite photo mosaic shows deployment of Curiosity rovers robotic arm and APXS X-ray spectrometer onto the ‘Winjana’ rock target at Mount Remarkable for evaluation as missions third drill target inside Gale Crater on Mars. The navcam raw images were stitched together from several Martian days up to Sol 612, April 26, 2014 and colorized. Credit: NASA/JPL-Caltech/Ken Kremer – kenkremer.com/Marco Di Lorenzo
See more Curiosity photo mosaics below[/caption]

To Drill or not to Drill?

That’s the momentous question posed by the international team of scientists and engineers who commanded NASA’s SUV sized Curiosity rover to reach out with her high tech robotic arm this weekend (Apr 25-27) and gather critical science measurements for high powered scrutiny of an outcrop on a Martian butte named Mount Remarkable.

See our multisol, composite photo mosaic – above – illustrating Curiosity’s arm in action pressing down her X-ray spectrometer on Saturday, April 26, Sol 612, at an alien rock on Mount Remarkable at the current stopping point at “The Kimberley Waypoint” along the epic trek to towering Mount Sharp.

Via a combination of laser shots, images, brushings and spectrometry the team is pondering new data streaming back daily across hundreds of millions of kilometers of interplanetary space to Earth to determine whether to bore into a sandstone slab being evaluated as the target for the missions third drilling campaign.

The team deployed the arm this weekend onto a rock target called “Windjana,” after a gorge in Western Australia.

Curiosity’s Panoramic view of Mount Remarkable at ‘The Kimberley Waypoint’ where rover will conduct 3rd drilling campaign inside Gale Crater on Mars. The navcam raw images were taken on Sol 603, April 17, 2014, stitched and colorized. Credit: NASA/JPL-Caltech/Ken Kremer - kenkremer.com/Marco Di Lorenzo — Curiosity’s Panoramic view of Mount Remarkable at ‘The Kimberley Waypoint’ where rover will conduct 3rd drilling campaign inside Gale Crater on Mars. The navcam raw images were taken on Sol 603, April 17, 2014, stitched and colorized. Credit: NASA/JPL-Caltech/Ken Kremer – kenkremer.com/Marco Di Lorenzo

After confirming that the 1 ton robot was in a stable position, the team commanded study observations on Saturday, Sol 612, using the APXS spectrometer and MAHLI camera on the terminus of the arm’s turret.

“The observation will document its chemical composition and morphology before drilling,” says science team member Ken Herkenoff in a mission update.

She also brushed off the potential ‘Windjana’ drill target with the wire-bristle Dust Removal Tool (DRT) to clear away obscuring Red Planet dirt and dust hindering the data collections.

NASA's Curiosity Mars rover has driven within robotic-arm's reach of the sandstone slab at the center of this April 23 view from the rover's Mast Camera. The rover team plans to have Curiosity examine a target patch on the rock, called "Windjana," to aid a decision about whether to drill there. Credit: NASA/JPL-Caltech/MSSS — NASA’s Curiosity Mars rover has driven within robotic-arm’s reach of the sandstone slab at the center of this April 23 view from the rover’s Mast Camera. The rover team plans to have Curiosity examine a target patch on the rock, called “Windjana,” to aid a decision about whether to drill there. Credit: NASA/JPL-Caltech/MSSS

The rover is also conducting continuing remote sensing observations with the ChemCam, Mastcam and Navcam cameras mounted on the Mast.

Today, April 27, Sol 613, “MAHLI will take another selfie of the rover” according to Herkenhoff.

In early April, the six wheeled rover pulled into a scientifically enticing science destination known as “The Kimberley Waypoint” in hopes of carrying out the next drilling operation into alien Martian terrain in search of further clues about ancient Martian environments that may have been favorable for life.

“We are officially in ‘The Kimberley’ now,” Curiosity Principal Investigator John Grotzinger, of the California Institute of Technology, Pasadena, told me at that time.

Since arriving in the Kimberley region, Curiosity’s earth bound handlers have been maneuvering the 1 ton robot around to thoroughly survey destination “Kimberley” in choosing the best drill site.

Why was Kimberley chosen as a science destination ?

“The Kimberley” has interesting, complex stratigraphy,” Grotzinger told me.

If Windjana meets the required criteria, Curiosity will bore into the sandstone rock, and then pulverize and filter it prior to delivery to the two onboard miniaturized chemistry labs – SAM and CheMin.

Windjana would be the first sandstone drill target, if selected. The first two drill locations at ‘John Klein’ and ‘Cumberland’ inside Yellowknife Bay were mudstone.

Curiosity scans scientifically intriguing rock outcrops of gorgeous Martian terrain at ‘The Kimberley’ waypoint in search of next drilling location beside Mount Remarkable butte, at right. Mastcam color photo mosaic assembled from raw images snapped on Sol 590, April 4, 2014. Credit: NASA/JPL/MSSS/Marco Di Lorenzo/Ken Kremer - kenkremer.com — Curiosity scans scientifically intriguing rock outcrops of gorgeous Martian terrain at ‘The Kimberley’ waypoint in search of next drilling location beside Mount Remarkable butte, at right. Mastcam color photo mosaic assembled from raw images snapped on Sol 590, April 4, 2014. Credit: NASA/JPL/MSSS/Marco Di Lorenzo/Ken Kremer – kenkremer.com

Curiosity departed the ancient lakebed at the Yellowknife Bay region in July 2013 where she discovered a habitable zone with the key chemical elements and a chemical energy source that could have supported microbial life billions of years ago – and thereby accomplished the primary goal of the mission.

“We want to learn more about the wet process that turned sand deposits into sandstone here,” said Grotzinger, in a NASA statement.

“What was the composition of the fluids that bound the grains together? That aqueous chemistry is part of the habitability story we’re investigating.”

“Understanding why some sandstones in the area are harder than others also could help explain major shapes of the landscape where Curiosity is working inside Gale Crater. Erosion-resistant sandstone forms a capping layer of mesas and buttes. It could even hold hints about why Gale Crater has a large layered mountain, Mount Sharp, at its center,” NASA elaborated in the statement.

To date, Curiosity’s odometer totals 3.8 miles (6.1 kilometers) since landing inside Gale Crater on Mars in August 2012. She has taken over 143,000 images.

The sedimentary foothills of Mount Sharp, which reaches 3.4 miles (5.5 km) into the Martian sky, is the 1 ton robots ultimate destination inside Gale Crater because it holds caches of water altered minerals. Such minerals could possibly indicate locations that sustained potential Martian life forms, past or present, if they ever existed.

Curiosity has some 4 kilometers to go to reach the base of Mount Sharp sometime later this year.

Martian landscape with rows of curved rock outcrops at ‘Kimberly’ in the foreground and spectacular Mount Sharp on the horizon. NASA’s Curiosity Mars rover pulled into Kimberly waypoint dominated by layered rock outcrops as likely drilling site. This colorized navcam camera photomosaic was assembled from imagery taken on Sol 576 (Mar. 20, 2014). Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer-kenkremer.com

Stay tuned here for Ken’s continuing Curiosity, Opportunity, Chang’e-3, SpaceX, Orbital Sciences, LADEE, MAVEN, MOM, Mars and more planetary and human spaceflight news.

Ken Kremer

Curiosity Mars rover captured this panoramic view of a butte called "Mount Remarkable" and surrounding outcrops at “The Kimberley " waypoint on April 11, 2014, Sol 597. Colorized navcam photomosaic was stitched by Marco Di Lorenzo and Ken Kremer. Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer - kenkremer.com — Curiosity Mars rover captured this panoramic view of a butte called “Mount Remarkable” and surrounding outcrops at “The Kimberley ” waypoint on April 11, 2014, Sol 597. Colorized navcam photomosaic was stitched by Marco Di Lorenzo and Ken Kremer. Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer – kenkremer.com

April 25, 2014December 23, 2015 by Jason Major

Imagine What Could Be Done With a “Penny4NASA”

NASA's % of the U.S. budget over the years

If you’re reading this then you’re probably a big fan of space exploration. And while on one hand you could say that we are now living in a “golden age” of exploration, what with the ongoing missions there are around the Solar System and the new discoveries being made on an almost weekly basis about our Universe, on the other hand it seems like we are getting more and more “grounded” as human explorers, with still years to go before the first footprints are made on Mars, an ever-growing span since we last walked on the Moon, and steadily-shrinking or stagnant budgets that can’t support all the missions that DO exist — and sometimes cancel them altogether.

“We have discovered amazing places. But imagine what’s hiding where we haven’t even looked?”

In order for missions to ever get off the ground, they need to be funded. Right now NASA — still arguably the leader in space exploration among world agencies — receives a little over 0.4 percent of every U.S. tax dollar. Less than half a penny. That’s what NASA explores the Solar System with, what makes our knowledge of the Universe — from the farthest visible reaches right down to our own planet Earth — even possible. What if NASA were to receive a full one percent? A whole penny from every dollar? That’d still be only a quarter of what NASA worked with to put men on the Moon in 1969, but it’d be more than double what it gets now.

A penny for NASA… this is the goal of Penny4NASA.org, an outreach group that strives to increase the funding — if just by a little — of the world’s most accomplished, inspirational, and powerful space exploration administration. (Before… you know, it isn’t.)

The video above was created for Penny4NASA by artist and animator Brad Goodspeed, and reminds us of what NASA has achieved in its 50-year history, of what its goals are (or at least should be) and, unfortunately, why many of them have remained unattained. NASA needs support — our support — or else its candles will stay unlit and our windows and doors to the Universe will slowly but surely close.

How can you help? Well for one thing, stay excited about space and science (and get others excited too!) Interest is the key to making sure people don’t lose sight of what’s happening in the field; you might be surprised to hear the misinformation that’s been passed around. (No, NASA isn’t “dead.”) And let your policy-makers know that space exploration and the investment in technology and innovation that goes along with it is important to you — the Planetary Society has a convenient page where you can find links to write to your state representative here. And finally you can support groups like Penny4NASA, made up of enthusiastic young professionals who want to see our nation’s past successes in space exploration continued into their future.

“America is fading right now. Nobody’s dreaming about tomorrow anymore. NASA knows how to dream about tomorrow — if the funding can accommodate it, if the funding can empower it.”
– Neil deGrasse Tyson

Want more inspiration? Read this excerpt from Neil deGrasse Tyson’s Space Chronicles on TheWeek.com here.

Video credit: Brad Goodspeed/Penny4NASA.org

April 24, 2014December 23, 2015 by Ken Kremer

Curiosity Captures First Ever Asteroid Images from Mars Surface

NASA's Curiosity Mars rover has caught the first image of asteroids taken from the surface of Mars. The image includes two asteroids, Ceres and Vesta. This version includes Mars' moon Deimos in a circular, exposure-adjusted inset and square insets at left from other observations the same night. Credit: NASA/JPL-Caltech/MSSS/Texas A&M

NASA’s Curiosity Mars rover has caught the first image of asteroids taken from the surface of Mars on April 20, 2014. The image includes two asteroids, Ceres and Vesta. This version includes Mars’ moon Deimos in a circular, exposure-adjusted inset and square insets at left from other observations the same night. Credit: NASA/JPL-Caltech/MSSS/Texas A&M
More night sky views and surface mosaics below[/caption]

The Curiosity rover has captured the first images of asteroids even taken by a Human probe from the alien surface of the Red Planet during night sky imaging.

And it’s not just one asteroid, but two asteroids caught in the same night time pointing on the Red Planet. Namely, asteroids Ceres and Vesta.

The stupendous image – seen above – was snapped by Curiosity’s high resolution Mastcam camera earlier this week on Sunday, April 20, 2014, Sol 606, whilst she was scanning about during daylight for her next drilling target at “The Kimberley” waypoint she pulled into at the start of this month.

Ceres and Vesta appear as streaks since the Mastcam image was taken as a 12 second time exposure.

“This imaging was part of an experiment checking the opacity of the atmosphere at night in Curiosity’s location on Mars, where water-ice clouds and hazes develop during this season,” said camera team member Mark Lemmon of Texas A&M University, College Station, in a statement.

“The two Martian moons were the main targets that night, but we chose a time when one of the moons was near Ceres and Vesta in the sky.”

View our “Kimberley” region photo mosiacs below to see exactly from where the six wheeled robot took the asteroid image shown above, while driving around the base of “Mount Remarkable”.

And those two asteroids are extra special because not only are they the two most massive objects in the Main asteroid belt between Mars and Jupiter, but they are also the destinations of another superlative NASA unmanned mission – Dawn.

The exotic Dawn probe, propelled by a stream of ions, orbited Vesta for a year in 2011 and is now approaching Ceres for an exciting orbital mission in 2015.

Ceres, the largest asteroid, is about 590 miles (950 kilometers) in diameter. Vesta is the third-largest object in the main belt and measures about 350 miles (563 kilometers) wide.

And as if Curiosity’s mouthwatering and heavenly double asteroid gaze wasn’t already spectacular enough, the tinier of Mars’ moons, Deimos, was also caught in that same image.

A trio of star trails is also seen, again due to the 12 second time exposure time.

Furthermore, Mars largest moon Phobos as well as massive planets Jupiter and Saturn were also visible that same Martian evening, albeit in a different pointing.

These celestial objects are all combined in the composite image above.

“The background is detector noise, limiting what we can see to magnitude 6 or 7, much like normal human eyesight. The two asteroids and three stars would be visible to someone of normal eyesight standing on Mars. Specks are effects of cosmic rays striking the camera’s light detector,” says NASA.

An unannotated image is seen below.

Curiosity’s makers back on Earth are nowhere to be seen. But check out the Curiosity’s earlier photo below of the Earth and Moon from my prior article – here.

To date, Curiosity’s odometer totals 3.8 miles (6.1 kilometers) since landing inside Gale Crater on Mars in August 2012. She has taken over 143,000 images.

Curiosity has some 4 kilometers to go to reach the base of Mount Sharp sometime later this year.

Stay tuned here for Ken’s continuing Curiosity, Opportunity, Chang’e-3, SpaceX, Orbital Sciences, LADEE, MAVEN, MOM, Mars and more planetary and human spaceflight news.

Ken Kremer

You are here! – As an Evening Star in the Martian Sky. This evening-sky view taken by NASA’s Mars rover Curiosity shows the Earth and Earth’s moon as seen on Jan. 31, 2014, or Sol 529 shortly after sunset at the Dingo Gap inside Gale Crater. Credit: NASA/JPL-Caltech/MSSS/TAMU — You are here! – As an Evening Star in the Martian Sky
This evening-sky view taken by NASA’s Mars rover Curiosity shows the Earth and Earth’s moon as seen on Jan. 31, 2014, or Sol 529 shortly after sunset at the Dingo Gap inside Gale Crater. Credit: NASA/JPL-Caltech/MSSS/TAMU

Mars rock rows and Mount Sharp. Martian landscape scene with rows of striated rocks in the foreground and Mount Sharp on the horizon. NASA's Curiosity Mars rover paused mid drive at the Junda outcrop to snap the component images for this navcam camera photomosaic on Sol 548 (Feb. 19, 2014) and then continued traveling southwards towards mountain base. UHF Antenna at right. Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer-kenkremer.com — Mars rock rows and Mount Sharp. Martian landscape scene with rows of striated rocks in the foreground and Mount Sharp on the horizon. NASA’s Curiosity Mars rover paused mid drive at the Junda outcrop to snap the component images for this navcam camera photomosaic on Sol 548 (Feb. 19, 2014) and then continued traveling southwards towards mountain base. UHF Antenna at right. Credit: NASA/JPL-Caltech/Marco Di Lorenzo/Ken Kremer-kenkremer.com

April 23, 2014May 12, 2018 by Elizabeth Howell

The Inner and Outer Planets in Our Solar System

The Solar System. Credit: spaceplace.nasa.gov

In our Solar System, astronomers often divide the planets into two groups — the inner planets and the outer planets. The inner planets are closer to the Sun and are smaller and rockier. The outer planets are further away, larger and made up mostly of gas.

The inner planets (in order of distance from the sun, closest to furthest) are Mercury, Venus, Earth and Mars. After an asteroid belt comes the outer planets, Jupiter, Saturn, Uranus and Neptune. The interesting thing is, in some other planetary systems discovered, the gas giants are actually quite close to the sun.

This makes predicting how our Solar System formed an interesting exercise for astronomers. Conventional wisdom is that the young Sun blew the gases into the outer fringes of the Solar System and that is why there are such large gas giants there. However, some extrasolar systems have “hot Jupiters” that orbit close to their Sun.

The Inner Planets:

The four inner planets are called terrestrial planets because their surfaces are solid (and, as the name implies, somewhat similar to Earth — although the term can be misleading because each of the four has vastly different environments). They’re made up mostly of heavy metals such as iron and nickel, and have either no moons or few moons. Below are brief descriptions of each of these planets based on this information from NASA.

Mercury: Mercury is the smallest planet in our Solar System and also the closest. It rotates slowly (59 Earth days) relative to the time it takes to rotate around the sun (88 days). The planet has no moons, but has a tenuous atmosphere (exosphere) containing oxygen, sodium, hydrogen, helium and potassium. The NASA MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) spacecraft is currently orbiting the planet.

The terrestrial planets of our Solar System at approximately relative sizes. From left, Mercury, Venus, Earth and Mars. Credit: Lunar and Planetary Institute

Venus: Venus was once considered a twin planet to Earth, until astronomers discovered its surface is at a lead-melting temperature of 900 degrees Fahrenheit (480 degrees Celsius). The planet is also a slow rotator, with a 243-day long Venusian day and an orbit around the sun at 225 days. Its atmosphere is thick and contains carbon dioxide and nitrogen. The planet has no rings or moons and is currently being visited by the European Space Agency’s Venus Express spacecraft.

Earth: Earth is the only planet with life as we know it, but astronomers have found some nearly Earth-sized planets outside of our solar system in what could be habitable regions of their respective stars. It contains an atmosphere of nitrogen and oxygen, and has one moon and no rings. Many spacecraft circle our planet to provide telecommunications, weather information and other services.

Mars: Mars is a planet under intense study because it shows signs of liquid water flowing on its surface in the ancient past. Today, however, its atmosphere is a wispy mix of carbon dioxide, nitrogen and argon. It has two tiny moons (Phobos and Deimos) and no rings. A Mars day is slightly longer than 24 Earth hours and it takes the planet about 687 Earth days to circle the Sun. There’s a small fleet of orbiters and rovers at Mars right now, including the large NASA Curiosity rover that landed in 2012.

The Outer Planets:

The outer planets (sometimes called Jovian planets or gas giants) are huge planets swaddled in gas. They all have rings and all of plenty of moons each. Despite their size, only two of them are visible without telescopes: Jupiter and Saturn. Uranus and Neptune were the first planets discovered since antiquity, and showed astronomers the solar system was bigger than previously thought. Below are brief descriptions of each of these planets based on this information from NASA.

Jupiter: Jupiter is the largest planet in our Solar System and spins very rapidly (10 Earth hours) relative to its orbit of the sun (12 Earth years). Its thick atmosphere is mostly made up of hydrogen and helium, perhaps surrounding a terrestrial core that is about Earth’s size. The planet has dozens of moons, some faint rings and a Great Red Spot — a raging storm happening for the past 400 years at least (since we were able to view it through telescopes). NASA’s Juno spacecraft is en route and will visit there in 2016.

Saturn: Saturn is best known for its prominent ring system — seven known rings with well-defined divisions and gaps between them. How the rings got there is one subject under investigation. It also has dozens of moons. Its atmosphere is mostly hydrogen and helium, and it also rotates quickly (10.7 Earth hours) relative to its time to circle the Sun (29 Earth years). Saturn is currently being visited by the Cassini spacecraft, which will fly closer to the planet’s rings in the coming years.

Near-infrared views of Uranus reveal its otherwise faint ring system, highlighting the extent to which it is tilted. Credit: Lawrence Sromovsky, (Univ. Wisconsin-Madison), Keck Observatory.

Uranus: Uranus was first discovered by William Herschel in 1781. The planet’s day takes about 17 Earth hours and one orbit around the Sun takes 84 Earth years. Its mass contains water, methane, ammonia, hydrogen and helium surrounding a rocky core. It has dozens of moons and a faint ring system. There are no spacecraft slated to visit Uranus right now; the last visitor was Voyager 2 in 1986.

Neptune: Neptune is a distant planet that contains water, ammmonia, methane, hydrogen and helium and a possible Earth-sized core. It has more than a dozen moons and six rings. The only spacecraft to ever visit it was NASA’s Voyager 2 in 1989.

To learn more about the planets and missions, check out these links:

Solar System Exploration: Planets (NASA)
NASA Photojournal (NASA)
Missions (NASA)
Space Science (European Space Agency)
USGS Astrogeology (U.S. Geological Survey)
The Solar System And Its Planets (European Space Agency)

April 21, 2014July 26, 2016 by Elizabeth Howell

How Far Are The Planets From The Sun?

Artist's impression of the planets in our solar system, along with the Sun (at bottom). Credit: NASA

The eight planets in our solar system each occupy their own orbits around the Sun. They orbit the star in ellipses, which means their distance to the sun varies depending on where they are in their orbits. When they get closest to the Sun, it’s called perihelion, and when it’s farthest away, it’s called aphelion.

So to talk about how far the planets are from the sun is a difficult question, not only because their distances constantly change, but also because the spans are so immense — making it hard for a human to grasp. For this reason, astronomers often use a term called astronomical unit, representing the distance from the Earth to the Sun.

The table below (first created by Universe Today founder Fraser Cain in 2008) shows all the planets and their distance to the Sun, as well as how close these planets get to Earth.

Mercury:

Closest: 46 million km / 29 million miles (.307 AU)
Farthest: 70 million km / 43 million miles (.466 AU)
Average: 57 million km / 35 million miles (.387 AU)
Closest to Mercury from Earth: 77.3 million km / 48 million miles

Venus:

Closest: 107 million km / 66 million miles (.718 AU)
Farthest: 109 million km / 68 million miles (.728 AU)
Average: 108 million km / 67 million miles (.722 AU)
Closest to Venus from Earth: 40 million km / 25 million miles

Earth:

Closest: 147 million km / 91 million miles (.98 AU)
Farthest: 152 million km / 94 million miles (1.01 AU)
Average: 150 million km / 93 million miles (1 AU)

Mars:

Closest: 205 million km / 127 million miles (1.38 AU)
Farthest: 249 million km / 155 million miles (1.66 AU)
Average: 228 million km / 142 million miles (1.52 AU)
Closest to Mars from Earth: 55 million km / 34 million miles

Jupiter:

Closest: 741 million km /460 million miles (4.95 AU)
Farthest: 817 million km / 508 million miles (5.46 AU)
Average: 779 million km / 484 million miles (5.20 AU)
Closest to Jupiter from Earth: 588 million km / 346 million miles

Saturn:

Closest: 1.35 billion km / 839 million miles (9.05 AU)
Farthest: 1.51 billion km / 938 million miles (10.12 AU)
Average: 1.43 billion km / 889 million miles (9.58 AU)
Closest to Saturn from Earth: 1.2 billion km /746 million miles

Uranus:

Closest: 2.75 billion km / 1.71 billion miles (18.4 AU)
Farthest: 3.00 billion km / 1.86 billion miles (20.1 AU)
Average: 2.88 billion km / 1.79 billion miles (19.2 AU)
Closest to Uranus from Earth: 2.57 billion km / 1.6 billion miles

Neptune:

Closest: 4.45 billion km /2.77 billion miles (29.8 AU)
Farthest: 4.55 billion km / 2.83 billion miles (30.4 AU)
Average: 4.50 billion km / 2.8 billion miles (30.1 AU)
Closest to Neptune from Earth: 4.3 billion km / 2.7 billion miles

As a special bonus, we’ll include Pluto too, even though Pluto is not a planet anymore.

Uranus and Neptune, the Solar System’s ice giant planets. (Images from Wikipedia.) — *Uranus and Neptune, the Solar System’s ice giant planets. Credit: Wikipedia Commons*

Pluto:

Closest: 4.44 billion km / 2.76 billion miles (29.7 AU)
Farthest: 7.38 billion km / 4.59 billion miles (49.3 AU)
Average: 5.91 billion km / 3.67 billion miles (39.5 AU)
Closest to Pluto from Earth: 4.28 billion km / 2.66 billion miles

To learn more:

Online resources demonstrating the scale of the Solar System:

If The Moon Were Only A Pixel (Josh Worth Art & Design)
Scale Model Of Our Solar System (University of Manitoba)
Build A Solar System (Exploratorium)
Scale Solar System (Josh Wetenkamp)

Many cities and countries have also installed scale models of the Solar System, such as:

Voyage Scale Solar System (Washington, D.C.)
Sagan Planet Walk (Ithaca, N.Y.)
Maine Solar System Model
Sweden Solar System
Planet Walk (Munich, Germany)
The Solar System (Brittany, France; website in French only)
Solar System Drive (Australia)

April 21, 2014May 12, 2018 by Elizabeth Howell

The Planets in Our Solar System in Order of Size

Planets in our Solar system size comparison. Largest to smallest are pictured left to right, top to bottom: Jupiter, Saturn, Uranus, Neptune, Earth, Venus, Mars, Mercury. Via Wikimedia Commons.

If you’re interested in planets, the good news is there’s plenty of variety to choose from in our own Solar System. From the ringed beauty of Saturn, to the massive hulk of Jupiter, to the lead-melting temperatures on Venus, each planet in our solar system is unique — with its own environment and own story to tell about the history of our Solar System.

What also is amazing is the sheer size difference of planets. While humans think of Earth as a large planet, in reality it is dwarfed by the massive gas giants lurking at the outer edges of our Solar System. This article explores the planets in order of size, with a bit of context as to how they got that way.

A Short History of the Solar System:

No human was around 4.5 billion years ago when the Solar System was formed, so what we know about its birth comes from several sources: examining rocks on Earth and other places, looking at other solar systems in formation and doing computer models, among other methods. As more information comes in, some of our theories of the Solar System must change to suit the new evidence.

Today, scientists believe the Solar System began with a spinning gas and dust cloud. Gravitational attraction at its center eventually collapsed to form the Sun. Some theories say that the young Sun’s energy began pushing the lighter particles of gas away, while larger, more solid particles such as dust remained closer in.

Artist's conception of a solar system in formation. Credit: NASA/FUSE/Lynette Cook — Artist’s conception of a solar system in formation. Credit: NASA/FUSE/Lynette Cook

Over millions and millions of years, the gas and dust particles became attracted to each other by their mutual gravities and began to combine or crash. As larger balls of matter formed, they swept the smaller particles away and eventually cleared their orbits. That led to the birth of Earth and the other eight planets in our Solar System. Since much of the gas ended up in the outer parts of the system, this may explain why there are gas giants — although this presumption may not be true for other solar systems discovered in the universe.

Until the 1990s, scientists only knew of planets in our own Solar System and at that point accepted there were nine planets. As telescope technology improved, however, two things happened. Scientists discovered exoplanets, or planets that are outside of our solar system. This began with finding massive planets many times larger than Jupiter, and then eventually finding planets that are rocky — even a few that are close to Earth’s size itself.

The other change was finding worlds similar to Pluto, then considered the Solar System’s furthest planet, far out in our own Solar System. At first astronomers began treating these new worlds like planets, but as more information came in, the International Astronomical Union held a meeting to better figure out the definition.

Hubble image of Pluto and some of its moons, Charon, Nix and Hydra. Image Credit: NASA, ESA, H. Weaver (JHU/APL), A. Stern (SwRI), and the HST Pluto Companion Search Team

The result was redefining Pluto and worlds like it as a dwarf planet. This is the current IAU planet definition:

“A celestial body that (a) is in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighborhood around its orbit.”

Size of the Eight Planets:

According to NASA, this is the estimated radii of the eight planets in our solar system, in order of size. We also have included the radii sizes relative to Earth to help you picture them better.

Jupiter (69,911 km / 43,441 miles) – 1,120% the size of Earth
Saturn (58,232 km / 36,184 miles) – 945% the size of Earth
Uranus (25,362 km / 15,759 miles) – 400% the size of Earth
Neptune (24,622 km / 15,299 miles) – 388% the size of Earth
Earth (6,371 km / 3,959 miles)
Venus (6,052 km / 3,761 miles) – 95% the size of Earth
Mars (3,390 km / 2,460 miles) – 53% the size of Earth
Mercury (2,440 km / 1,516 miles) – 38% the size of Earth

Eight planets and a dwarf planet in our Solar System, approximately to scale. Pluto is a dwarf planet at far right. At far left is the Sun. The planets are, from left, Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Credit: Lunar and Planetary Institute

Jupiter is the behemoth of the Solar System and is believed to be responsible for influencing the path of smaller objects that drift by its massive bulk. Sometimes it will send comets or asteroids into the inner solar system, and sometimes it will divert those away.

Saturn, most famous for its rings, also hosts dozens of moons — including Titan, which has its own atmosphere. Joining it in the outer solar system are Uranus and Neptune, which both have atmospheres of hydrogen, helium and methane. Uranus also rotates opposite to other planets in the solar system.

The inner planets include Venus (once considered Earth’s twin, at least until its hot surface was discovered); Mars (a planet where liquid water could have flowed in the past); Mercury (which despite being close to the sun, has ice at its poles) and Earth, the only planet known so far to have life.

To learn more about the Solar System, check out these resources:

Planets (NASA)
Solar System (USGS)
Exploring the Planets (National Air and Space Museum)
Windows to the Universe (National Earth Science Teachers Association)
Solar System (National Geographic, requires free registration)

April 18, 2014April 26, 2016 by Jason Major

Ancient Martian Life May Be Preserved in Glass

A fresh impact left this 30-meter-wide crater on Mars, imaged by HiRISE in Nov. 2013 (NASA/JPL-Caltech/Univ. of Arizona )

When large asteroids or comets strike the Earth — as they have countless times throughout our planet’s history — the energy released in the event creates an enormous amount of heat, enough to briefly melt rock and soil at the impact site. That molten material quickly cools, trapping organic material and bits of plants and preserving them inside fragments of glass for tens of thousands, even millions of years.

Researchers studying impact debris on Earth think that the same thing could very well have happened on Mars, and that any evidence for ancient life on the Red Planet might be found by looking inside the glass.

A research team led by Pete Schultz, a geologist at Brown University in Providence, Rhode Island, has identified the remains of plant materials trapped inside impact glass found at several different sites scattered across Argentina, according to a university news release issued Friday, April 18.

Melt breccias from two impact events in particular, dating back 3 and 9 million years, were discovered to contain very well-preserved fragments of vegetation — providing not only samples of ancient organisms but also snapshots of the local environment from the time of the events.

An asteroid impacts ancient Mars and send rocks hurtling to space - some reach Earth — Mars experienced many large impact events in its early history, just like Earth

“These glasses preserve plant morphology from macro features all the way down to the micron scale,” said Schultz. “It’s really remarkable.”

Schultz believes that the same process that trapped once-living material in Argentina’s Pampas region — which is covered with windblown, Mars-like sediment, especially in the west — may have occurred on Mars, preserving any early organics located at and around impact sites.

“Impact glass may be where the 4 billion-year-old signs of life are hiding,” Schultz said. “On Mars they’re probably not going to come out screaming in the form of a plant, but we may find traces of organic compounds, which would be really exciting.”

The research has been published in the latest issue of Geology Magazine.

Um, You Can See a Car on Mars

A recent image taken by the HiRISE camera on the Mars Reconnaissance Orbiter of the Curiosity rover in "The Kimberly" area in Gale Crater on Mars. Credit: NASA/JPL/University of Arizona

First of all, I completely stole this headline from NASA engineer Bobak Ferdowski (AKA The Mohawk Guy) on Twitter. Second, this is just a great image of the Curiosity rover sitting on Mars, including views of its tracks and where it did a wheelie or two. Plus, where the rover now sits is a very intriguing region called “The Kimberly.” Curiosity will soon whip out its drill to see if it can find hints of organic material, which could be a biomarker — the holy grail of Mars exploration.

Find out why this is such an intriguing region in this video:

Um, you can see a car on Mars. MT“@HiRISE: Curiosity Ready to Drill http://t.co/jpCf2q0mHB pic.twitter.com/WQSsmMzc99”

— Bobak Ferdowsi (@tweetsoutloud) April 16, 2014

Source: HiRISE

April 11, 2014December 19, 2015 by Fraser Cain

Weekly Space Hangout – April 11, 2014: Exomoons, Eclipses & Launches

Host: Fraser Cain
Astrojournalist: Morgan Rehnberg(cosmicchatter.org / @cosmic_chatter)
Continue reading “Weekly Space Hangout – April 11, 2014: Exomoons, Eclipses & Launches”

April 10, 2014December 23, 2015 by Jason Major

JPL Tests Big with a Supersonic Parachute for Mars

No rocket sleds were harmed in the making of this video. (NASA/JPL)

“You wanna go to Mars, you wanna go big? Then you gotta test big here,” says mechanical engineer Michael Meacham, and testing big is exactly what he and other engineers at NASA’s Jet Propulsion Laboratory have done to develop a new supersonic parachute for future Mars landings.

The process of putting things onto Mars has traditionally used the same couple of tried-and-true methods: inflatable, shock-absorbing bouncers and large parachutes combined with retro-rockets (most recently seen in the famous “Seven Minutes of Terror” Curiosity landing in August 2012.) But both methods are limited in how large and massive of an object can safely be placed on the Martian surface. For even larger-scale future missions, new technology will have to be developed to make successful landings possible.

Enter the LDSD, or Low-Density Supersonic Decelerator, an enormous parachute — similar to the one used by Curiosity except bigger — that can slow the descent of even more massive payloads through the thin Martian atmosphere.

Of course, part of the development process is testing. And in order to run such a large chute through the same sorts of rigors it would experience during an actual Mars landing, JPL engineers had to step outside of the wind tunnel and devise another method.

The one they came up with involves a rocket sled, a Night Hawk helicopter, a 100-lb steel bullet, a kilometer-long cable (and lots and lots of math.) It’s an experiment worthy of “Mythbusters”… watch the video above to see how it turned out.

“When we land spacecraft on Mars, we’re going extremely fast… we have got to slow down. So we use a parachute. And we use a really BIG parachute.”
– Michael Meacham, Mechanical Engineer at JPL