Category: Guide to Space

Mars mass is 6.4169 x 10²³ kg. That is slightly more than 10% of the Earth’s mass. Mars is a tiny world in every way when compared to Earth. In our Solar System, Mars is the second smallest planet by mass. Only Mercury is smaller. While Mars is a tiny planet, it is the most explored outside of our own. Here are a few Mars missions and some of the discoveries that each made.

Mariner 3 and 4 were meant to be sister missions to Mars. Mariner 3 failed shortly after launch, but Mariner 4 arrived in Martian orbit after an 8 month journey. It is credited with returning the first images from another planet. It was able to show large impact craters that appeared to have frost on them. The spacecraft and its equipment were crude by modern standards.

We will skip a few missions and move to the Phoenix Lander. This mission’s objective was to confirm the presence of water ice underneath the Martian surface. This water ice had been theorized for quite some time, but lacked confirmation. On June 19, 2008, NASA announced that bits of bright material in a trench dug by the lander’s robotic arm had disappeared over the course of four days. This implied that they were composed of water ice. Initially, they were thought to be water ice or carbon dioxide ice(dry ice) In the conditions on Mars dry ice would have disappeared much faster. Phoenix later confirmed the presence of water ice on Mars using a mass spectrometer. When a soil sample was heated, water vapor appeared as the sample heated to 0 degrees Celsius.

The Mars Express is one of several spacecraft currently exploring Mars. It has sent back images and data the strongly suggest that the Martian environment is much different today than it was a few billion years ago. Interpretation of the data shows that Mars was once a warm and wet world with rivers and oceans dotting its surface. No evidence of past vegetation or life has been found, but proof of liquid water in the planet’s past is intriguing enough.

Knowing Mars mass is enough to answer one question on a test or in a paper, but, to understand the planet, you will have to do quite a bit more research. You will not be alone. NASA scientists are planning at least four more missions by 2020 including a mission to return samples of the Martian soil. The goal is to understand Mars well enough to send a manned flight to the Red Planet.

Here’s a great article about how difficult it will be to land large loads on Mars.

This site lets you calculate your weight on other worlds. And here’s NASA’s fact sheet on Mars.

Finally, if you’d like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars.

Sources:
NASA: Mars Facts
NASA: Mars Missions

Mar’s surface is a dry, barren wasteland marked by old volcanoes and impact craters. The entire surface can be scoured by a single sand storm that hides it from observation for days at a time. Despite the formidable conditions, Mar’s surface is better understood by scientists than any other part of the Solar System, except our own planet, of course.

Mars is a small world. Its radius is half of the Earth’s and it has a mass that is less than one tenth. The Red Planet’s total surface area is about 28% of Earth. While that does not sound like a large world at all, it is nearly equivalent to all of the dry land on Earth. The surface is thought to be mostly basalt, covered by a fine layer of iron oxide dust that has the consistency of talcum powder. Iron oxide(rust as it is commonly called) gives the planet its characteristic red hue.

In the ancient past of the planet volcanoes were able to erupt for millions of years unabated. A single hotspot could dump molten rock on the surface for millenia because Mars lacks plate tectonics. The lack of tectonics means that the same rupture in the surface stayed open until there was no more pressure to force magma to the surface. Olympus Mons formed in this manner and is the largest mountain in the Solar System. It is three time taller than Mt. Everest. These runaway volcanic actions could also partially explain the deepest valley in the Solar System. Valles Marineris is thought to be the result of a collapse of the material between two hotspots and is also on Mars.

The Martian surface is dotted with impact craters. Most of these craters are still intact because there are no environmental forces to erode them. The planet lacks the wind, rain, and plate tectonics that cause erosion here on Earth. The atmosphere is much thinner than Earth’s so smaller meteorites are able to impact the planet.

Mar’s surface is believed to be much different than it was billions of years ago. Data returned by rovers and orbiters has shown that there are many minerals and erosion patterns on the planet that indicate liquid water in the past. It is possible that small oceans and long rivers once dominated the landscape. The last vestiges of that water are trapped as water ice below the surface. Scientists hope to analyze some of that ice and discover hidden Martian treasures.

How seasonal jets darken the surface of Mars, and how ice depth varies across Mars.

Want to explore the surface of Mars, check it out with Google Mars. Here is some more information about surface features on Mars.

Finally, if you’d like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars.

Sources:
http://solarsystem.nasa.gov/planets/profile.cfm?Object=Mars
http://search.nasa.gov/search/search.jsp?nasaInclude=mars+planet

The air on Mars would kill a human quickly. The atmosphere is less than 1% of Earth’s, so it would be hard to breath. What you would have available to your lungs would be undesirable to say the least. The air on Mars consists of 95% carbon dioxide, 3% nitrogen, 1.6% argon, and the remainder is trace amounts of oxygen, water vapor, and other gases.

On Earth, oxygen accounts for an average of 21% of the air that we breath. Humans can survive on lower concentrations, but not much lower. Oxygen is spread throughout our bodies by our red blood cells and our bodies thrive. The high concentration of carbon dioxide in the Martian atmosphere would replace oxygen in our red blood cells and the average human would die in less than 3 minutes if left unprotected on the surface. Of course, that assumes that air quality is the only factor considered. The cold and other factors would probably kill someone faster than the poor air quality.

We think of Mars as a dry, dead planet. That is fairly accurate, but at night the planet achieves 100% humidity. During the day it is very dry, here is why. Humidity is the amount of water vapor in the air. It varies daily and depends on the temperature: warm air can hold more water vapor than cold air . Humidity is measured as a percentage of the maximum amount of water that the air can hold at a given temperature. The greater the difference between the two temperatures, the greater the evaporation. When there is a lot of evaporation, the air is drier and the humidity is low. On Mars, the air is saturated (100% humidity) at night, but undersaturated during the day. This is because of the huge temperature difference between day and night.

The air on Mars was much different early in the history of the Solar System. Many scientists believe that the planet was warm and had a thicker atmosphere. Unfortunately, the planet lacked two important ingredients: plate tectonics and a magnetic field. Had those developed, Mars could have developed enough oxygen to support lifeforms similar to those on Earth.

The air on Mars is a major deterrent to human exploration of the planet. Here is a link to a video showing a Russian experiment to overcome this challenge. For now, poor air quality and nearly two years in space will keep humans pondering manned flight to the planet, but who knows what the future will hold.

More information on the Martian atmosphere from David Darling’s Encyclopedia of Science.

Here’s an interesting video, where Russian volunteers test out breathing air on Mars.

Finally, if you’d like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars.

Source: NASA

Want to know the closest planet to Mars? Look down beneath your feet… you’re looking at it. That’s right, the closest planet to Mars is our own home planet: Earth.

During their orbits, Earth and Mars can get as close as about 55 million kilometers. Since both Earth and Mars orbit the Sun, they can also be on opposite sides of the Sun. At that point, the two planets can be as far as 400 million km apart.

Because of this vast range in distances between when Earth and Mars are close and far, you can see why Mars can be sometimes very bright in the sky, and hard to see other times.

Just for comparison, Mars only gets within 490 million km of Jupiter at its closest. So Mars is always closer to Earth, and the rest of the inner planets, than it is to Jupiter.

There are several images of Earth captured by spacecraft, either orbiting Mars, or roving around on its surface. If you could live on Mars, Earth would be a very bright object in the sky. Of course, since Earth’s orbit is inside the Mars orbit, our home planet would be an evening or morning star, just like the view of Venus from Earth.

And if you’re wondering how far Earth is from Mars, here’s the answer. And no, Mars isn’t going to look as big as the Moon in August; that’s a hoax.

The same question has been answered over at Wikianswers.

Finally, if you’d like to learn more about planet Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars.

Recently, while discussing what she had learned in class, my daughter asked me: ”does Mars have rings?”. She is ten and it is fun to see her interested in anything educational. Unfortunately, I had to tell her that no, Mars does not have rings. While saying no was disappointing, it left a good opportunity to teach her how planetary rings are formed..

Planetary ring systems are formed in two ways. The first is by ice and dust like those around the ice giants and similar to the rings around Saturn. Scientist believe that the particle have been captured by a planet’s gravity and are prevented from combining into a moon by that gravity. The rings are visible because of the light that the particles reflect. In the case of Saturn, some of the moons within the rings system have ice geysers that some scientist think are constantly replenishing the rings.

A second way that a planetary ring may form is through impact. If a large enough asteroid were to impact a planet, dust and rock debris would be thrown into space. That debris would then be captured by the planet’s gravity. Scientists believe that the debris will fall back to the planet, but do not know how long it would take.

Mars may develop a ring system in the future. Scientists know that Mar’s moon, Phobos, is in a decaying orbit around the planet. In anywhere from 10 million to 100 million years it will crash into the planet forming a ring system as the debris is ejected back into space. After a million or so years, that ring system will collapse back onto the planet’s surface, causing an extensive crater field.

That begs the question of how did Phobos find itself in such a predicament. Well, it is most likely a captured asteroid. Its orbit took it too close to Mars and it did not have enough velocity to escape the planet’s gravity. Many moons in our Solar System have come to orbit their primaries in this fashion. Usually, small moons are captured and large moons form in situ, so to speak.

Now you know the answer to ”does Mars have rings?” and a little about a rings in the planet’s future. Don’t forget to read up on Mar’s other moon Deimos and maybe look a little deeper into Phobos. If planetary rings interest you, NASA has plenty of information on their website.

Here’s an article the describes how Phobos will eventually crash into Mars. And here’s some more information about what Saturn’s rings are made of.

The Planetary Rings Node has many resources for Saturn’s rings. And here’s an article about potential rings around Pluto.

We’ve covered Mars in the past at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars. We also talk about Saturn’s rings in Episode 59: Saturn.

Sources:
http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/981027a.html
http://solarsystem.nasa.gov/planets/profile.cfm?Object=Mar_Phobos
http://apod.nasa.gov/apod/ap080414.html

There are many volcanoes on Mars. So many, that the planet is broken down into volcanic provinces for easier reference. Quite a few of them are very large because the planet has not had tectonic plate action for billions of years, so a single hotspot could flow unabated for millenia.

Olympus Mons is a shield volcano on Mars and it is the largest volcano in the Solar System. Located in the Tharsis region of the planet along with three other large volcanoes, Olympus Mons measures an incredible 27 km in height and is 3 times taller than Mount Everest. It is about 500 km in diameter. The mountain was formed from a single hotspot that flowed for thousands, if not millions, of years. The lack of plate tectonics that allowed this unhindered flow also prevented massive pressure buildups that would have blown the top off of the volcano, decreasing its overall height.

In the northern part of the Tharsis volcanic province is Alba Mons also known as Alba Patera. It is a unique volcanic structure for several reasons. The volcano features unnaturally low slopes formed by numerous and extensive lava flows. Its slopes are a mere 0.5 degrees. It has a double caldera feature with the central figure being 350 km wide and 1.5 km high. Flows from Alba Mons seem to extend 2,000 km north-south and 3,000 km east-west. The widespread flows make this one of the largest volcanoes in the Solar System by area. Some scientist point to the volcano’s antipodal location to the Hellas impact basin as a possible reason its formation. Seismic waves from the impact may have traveled through the planet causing a weakening of the crust at the point of origin for Alba Mons.

In the Elysium volcanic province there are three main volcanoes. The province covers an area that is about 2,000 km in diameter. The main volcanoes are Elysium Mons, Hecates Tholus, and Albor Tholus. The northwestern edge of the province is characterized by large channels that emerge from several valleys(grabens) on the flanks of Elysium Mons. The grabens may have formed from the subsurface release of large volumes of ground water. The channels are accompanied by associated sedimentary deposits possibly formed by mudflows. Elysium Mons is 375 km across and 14 km high. Hecates Tholus is 180 km across and 4.8 km high. Albor Tholus, the southern-most of the Elysium volcanoes, is 150 km in diameter and 4.1 km high.

There are many interesting volcanoes on Mars. The NASA source listed below will take you to a list of there Martian volcanoes and many details about each. Good luck with your research.

Here’s a Universe Today article about an ancient Mars volcano caldera, and information that volcanoes were active on Mars recently.

Here’s a cool slideshow of volcanoes on Mars, and more information about volcanism on Mars.

Finally, if you’d like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars.

Sources:
NASA
Wikipedia

As with the rest of the planets in the Solar System, Mars is believed to have formed out of the primitive solar nebula 4.5 billion years ago.

Instead of condensing directly, from dust particles to planet, Mars and the rest of the terrestrial planets probably started out as a collection of small particles. Dust particles clumped together to form larger and larger objects. Dust became sand, pebbles, rocks, asteroids, and eventually planetoids. The formation of Mars happened when these particles all came together.

The energy from all these collisions heated up planet Mars, giving it a molten core and volcanic activity. We can see evidence of the end of the planetary formation period because of the impact craters strewn across the surface of the planet. This period was called the late heavy bombardment period, and all the planets in the Solar System were devastated too.

Astronomers think that Mars is relatively small because Jupiter finished its own formation a little earlier, and scooped up most of the available material. The gravity from Jupiter also seems to have prevented the formation of another planet in between Mars and Jupiter; instead, we’ve just got the asteroid belt.

Although Mars doesn’t have active plate tectonics, and its volcanism ended millions of years ago, the planet is much more similar to Earth and Venus, and different to the Moon and Mercury. Mars is the only other world in the Solar System that has a transparent atmosphere, and surface conditions that could be considered somewhat habitable.

Here’s an article from Universe Today about why Mars might be so dry. And more information about where the water went on Mars.

Additional information about the history and formation of Mars. And even more information here.

Finally, if you’d like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars.

The orbit of Mars is the second most eccentric in the Solar System. Only Mercury’s orbit is more eccentric. At perihelion Mars is 206,655,215 km from the Sun and at aphelion it is 249,232,432 km distant. That is a variation of of just under 42,600,000 km. The average distance from Mars to the Sun (called the semi-major axis) is 228 million km. It takes Mars approximately 687 Earth days to complete on orbit. The orbit of a planet varies in relation to the gravitational influences of the bodies around it, so the eccentricity can change over time. AS recently as 1.35 million years ago, Mars was in a nearly circular orbit.

Mars, like all planets in the Solar System, is tilted along its axis(axial tilt). For Mars, the axial tilt is about 25.19 degrees. This tilt is similar to Earth’s, so Mars has seasons like ours. The Martian seasons are longer because a year on Mars is nearly twice as long as an Earth year. The dramatically changing distances between Mars’ aphelion and perihelion means that the seasons aren’t balanced like Earth. Mars is at its closest when its southern hemisphere is tilted towards the Sun. So the southern hemisphere experiences hotter summers than the northern hemisphere.

The orbit of Mars allows it to approach Earth at varying distances. It is easiest to observe when it is at its closest approach. Opposition occurs when Mars’ geocentric longitude is 180° different from the Sun’s. Opposition can occur as much as 8½ days before or after closest approach. The distance at close approach varies between about 54 and 103 million km due to their position in their orbits. The last Mars opposition was on January 29, 2010. The next will be on March 3, 2012(about 100 million km). The average time between the successive oppositions(synodic period) of Mars is 780 days. Mars made its closest approach to Earth in nearly 60,000 years(55,758,006 km) on August 27, 2003. While this was a record, it was only slightly closer than other close approaches.

The orbit of Mars is well understood and has been observed, and documented, for thousands of years. The planet’s short period of apparent retrograde motion was noted as early as 1534 B.C. After reading and understanding the planet’s orbit, you should research more about its atmosphere, gravity, and exploration. Only then will you have a grasp of a few of the mysteries surrounding the Red Planet.

Here’s an article about Martian ice ages in the past, related to tilt, and another about mid-latitude glaciers on Mars.

Here’s more general information about Mars. And here are some pages from NASA about the Mars Phoenix Lander mission.

Finally, if you’d like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars.

Source:
NASA

Mars is named after the Roman god of war. Many believe that ancient peoples associated Mars with bloodshed and war because of its red color. The Romans were not the only society to associate the planet with bloodshed. The ancient Babylonians called it Nergal, after their god of fire, war, and destruction. In keeping with the planet’s association with the god Mars, its symbol is a circle with an arrow pointing outwards from its right corner. This is meant to represent Mar’s shield and spear.

That information is not nearly enough to satisfy anyone’s interest in the Red Planet, so here are a few interesting facts about Mars and its environs.

The largest mountain in the Solar System is on Mars. Olympus Mons is 27 km tall. It is a shield volcano that was able to erupt for million of years because Mars does not have tectonic plate movement. This allowed the same volcanic hotspot to erupt undisturbed until the giant mountain was formed.

The chemical symbol for iron is the same as the astronomical symbol for Mars. This is fitting, since the planet gets its reddish appearance from the iron oxide in the dust on its surface.

A year on Mars lasts 686.98 Earth days or 1.88 Earth years. There are four seasons throughout the year like here on Earth, but each season is longer than a typical Earth season.

Mars is full of water. Not liquid water like we see here on Earth, but water ice under the surface and at the bottom of craters. There is even evidence that there may be ice inside of caves on the Martian surface. These deposits are safe from the solar radiation that bombards the surface, so they are able to stay in place.

Mars does not have a magnetic field at this time, but spacecraft have detected residual magnetism in rocks on the surface. That would suggest an active magnetic field millions, if not billions, of years ago. Scientist believe that the core of Mars has become too solid to rotate and is no longer capable of generating a dynamo effect. A dynamo effect is essential in producing a magnetic field.

These are just a few of the interesting facts beyond who Mars is named after. Pay special attention to information generated by the Mars Express spacecraft. It has turned up a great deal of interesting data on, and under, the Martian surface.

In case you’re wondering, here’s how Jupiter got its name.

Here’s some historical information on Mars, the god of war, and more on Ares, the Greek version of Mars.

Finally, if you’d like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars.

Sources:
NASA
Case Western Reserve University – Astronomy

The diameter of Mars is 6,792 km. That makes the Red Planet about 53% of the diameter of Earth. In addition to a smaller diameter, Mars has only 10% of Earth’s mass. Those are interesting pieces of information to have, but only give a small picture of what Mars is like. Here are some more facts about Mars.

The gravity on Mars is only 38% of that on Earth. That would present some interesting issues for any visitors to the planet as well as some challenges to long term colonization. The low gravity can also be connected to the near absence of a Martian atmosphere and the cold, dry environment. Gravity helps atmospheric gases to cling to a planet’s surface. Mars can only cling tenuously. What atmosphere that is present is high in carbon dioxide, so if the planet retained more of it, the surface would warm quickly through a greenhouse effect. The greenhouse effect would melt the subsurface ice that the Mars Express spacecraft has found, thus moistening the surface. There are many indications from different spacecraft that Mars was at one time a warmer, wetter world.

Mars is often perceived as a dead planet. Scientists had begun to accept that possibility until methane was detected in its atmosphere. The methane is most likely from a geologic source, but it has to be a large source. Methane is quickly destroyed in the Martian atmosphere in a variety of ways, so discovery of substantial methane indicates that an ongoing process is releasing it. The presence of the gas is of interest to scientists because organisms release much of Earth’s methane; however, other processes, like oxidation of iron, also release methane.

Mars lacks any tectonic plate movement. That may allow the source of the methane to release it in plumes. The lack of plate tectonics is also the reason that the largest mountain in the Solar System was able to form. Olympus Mons, on Mars, is a shield volcano that is 27 km tall and about 550 km across. The absence of plate tectonics allowed a single hotspot to pour molten material onto the surface uninterrupted for millions of years.

You started out wondering what the diameter of Mars is and, now, you have several interesting facts to ponder. Be sure to double check our facts on the NASA website and, hopefully, you will find much more to pique your interest.

And just in case you’ve heard this hoax going around, Mars will never look as big as the Moon in the sky. That’s a myth that got started back in 2003, and just won’t go away.

Here’s a 1928 research article where the diameter of Mars was accurately calculated. And then the sophisticated gravity measurement instrument on board NASA’s Mars Reconnaissance Orbiter, that can make extremely accurate gravity measurements of Mars.

Finally, if you’d like to learn more about Mars in general, we have done several podcast episodes about the Red Planet at Astronomy Cast. Episode 52: Mars, and Episode 91: The Search for Water on Mars.

Sources:
NASA: Mars
Harvard University
NASA: Mars Methane