Air on Mars

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

Does Mars Have Rings?

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.


Volcanoes on Mars

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.


Orbit of 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.


Mars is Named After…

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.

Case Western Reserve University – Astronomy

Diameter of Mars

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.

NASA: Mars
Harvard University
NASA: Mars Methane

Does Mars Have Seasons?

”Does Mars have seasons?” is an easy question to answer. Yes, Mars has seasons. The planet experiences all four seasons that the Earth does, but, since the year is longer on the planet, the axial tilt is different, and Mars has a more eccentric orbit than Earth, the seasons are not the same length as each other or the same in each hemisphere. Why does Mars have seasons? Because, like Earth, its axis is tilted away from the Sun.

On Mars, in the northern hemisphere to be exact, spring is the longest season. The Martian year is nearly twice as long as an Earth year(1.88 years), the seasons last longer as well. Here is how a Martian year in the north breaks down: Spring…7 months, Summer…6 months, Fall…5.3 months, and Winter…just over 4 months. Even in the summer months it is very cold. Temperatures at the height of the season may not top -20 C. In the south the temperatures can be as much as 30 C warmer during the same season. The great fluctuations in temperature and the difference in warmth between hemispheres can cause huge dust storms. Some can affect just a small area, while others can cover the entire planet. The larger storms usually occur when the planet is near its aphelion(closest point to the Sun). When there are global dust storms there is no way for scientists to visualize the planet’s surface.

Now that you have the answer to ”does Mars have seasons?”, you might wonder if the planet has always had the same climate. Most scientists doubt it has. Scientific evidence suggests that the planet has seen warmer and colder periods over its existence, much like Earth has. A radar instrument on the Mars Express has turned up water ice, a mineral mapping instrument has discovered chemicals formed in a wet environment, and its camera has picked out features on the surface formed by running water. The cameras also show a huge valley, Kasei Valles, that was probably carved by a gigantic glacier. Additional research has shown evidence of glaciers at varying latitudes. This would seem to indicate that the planet formerly had a different degree of axial tilt, which would have made for a much different environment and potential seasonal variations.

Mars does have seasons. They are not the same as the seasons the planet experienced millenia ago and may not be the same in the future. Earth has seen the same climate changes. Planetary evolution is ongoing, hopefully the spacecraft on and around the planet will tell us more, soon.

Here’s an article describing Spirit surviving 1000 days on Mars, going through all the seasons. And another on the discovery of mid-latitude glaciers on Mars, evidence that the planet was much more tilted in the past.

Here is some great information from the Adler Planetarium about the Martian climate and seasons. And some more detailed information from Malin Space Science Systems.

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.


How Cold is Mars?

How cold is Mars? Now, that is a fine question. The average temperature across the Martian surface is -63 C. Parts of Mars have been known to drop as low as -123 C. There are two main reasons that Mars is colder than Earth: it is farther from the Sun and it has an atmosphere that is too thin to retain heat.

The Martian atmosphere contains greenhouse gases that would cause a much warmer surface if the planet had the gravity and magnetic field that would allow it to hold onto gases. What little atmosphere(only 1% as thick as Earth’s) that clings to Mars is 95.32% carbon dioxide. As we know from experience here on Earth, higher amounts of CO2 cause higher temperatures. We call it a greenhouse gas and blame global warming on the increase in these gases. If Mars could hold its carbon dioxide content, there would be runaway global warming across the planet.

The gravity on Mars is only 38% as strong as it is here on Earth. That low gravity allows many of the gases needed to retain heat close to the surface to escape into space. The core of the planet is thought to be solid. Without a spinning, molten core Mars is unable to generate a magnetic field. Without a magnetic field, the solar wind and radiation constantly bombard the Martian atmosphere, blowing away another portion of the gases needed to heat the planet.

There is evidence that Mars has not always been a frigid planet. Some probe instruments on the Mars Express suggest that at one time Mars was warm enough to support liquid water. A radar instrument has found water ice, a mineral mapping instrument discovered chemicals only formed in a wet environment, and a camera has shown features formed by running water. The Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS) has probed down to thousands of meters finding water ice along the way. The OMEGA Visible and Infrared Mineralogical Mapping Spectrometer has detected clay-like minerals that form during long-term exposure to water, sulphates(a mineral that forms when water evaporates), and ferric oxide. Each indicate the long term presence of liquid water on the surface. Images from the High Resolution Stereo Camera(HRSC) show features that could only be formed by erosion from flowing water.

The quick answer to ”how cold is Mars?” is -63 C on average. If you look into the contributing factors of that temperature, you must also look into the planet’s past. Some scientists think that Mars could have been a lush jungle like planet if it had not lost its atmosphere.

How cold is Mars? Read this article and learn that Mars is REALLY cold. And evidence that Mars has been cold for billions of years.

More information on Mars is available Hubblesite’s News Releases about Mars. Here’s an article from about how microbes can survive cold temperatures, maybe even some day 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.

NASA Solar System Exploration Guide
NASA Mars Fact Sheet

How Far is Jupiter from Earth

The answer to “how far is Jupiter from Earth” can have a different answer every day of the year. The planets both travel in their elliptical orbits getting closer then farther apart. When Earth and Jupiter are at their closest to each other they are 628,743,036 km apart. At their most distant from each other they are 928,081,020 km apart. In astronomical units the distance varies from 4.2 AU to 6.2 AU.

All of the planets follow an elliptical orbit. When the planet is closest to the Sun it is called perihelion. When it is farthest it is called aphelion. The difference between perihelion and aphelion determines how eccentric an orbit is. Jupiter and Earth have two of the least eccentric orbits in our Solar System.

Earth and Jupiter are closest to each other when Earth is at aphelion and Jupiter is at perihelion. They are the most distant when they are on opposite sides of the Sun and both are at aphelion.

Jupiter is frequently the third brightest object in the night sky behind the Moon and Venus. When Earth and Jupiter are at their closest approach to each other, only the Moon can outshine the planet. Jupiter is so massive that it creates many effects throughout the Solar System. Some scientist believe that the tidal effects of Jupiter as it reaches perihelion could cause sunspots to increase in frequency. It is easy to understand how Jupiter could cause tidal effects when you consider that it is 318 times more massive than the Earth.

Despite its size, Jupiter rotates faster than any other planet in our Solar System. The speed of its rotation has flattened it more than some other planets. On Jupiter the poles are 4,600 km closer to the planet’s center than the equator is.

Jupiter’s mass and other aspects allow it to have a strong gravitational pull. That strong gravity has allowed the planet to capture many satellites. Currently, Jupiter is acknowledged to have 50 moons and 14 provisional moons. Many of those are thought to have been asteroids that were captured when they wandered too close to Jupiter’s influence.

The answer to ”how far is Jupiter from Earth” does not have a single clear cut answer. It varies day to day depending on the position of each planet in their respective orbits. There are many concrete answers about the planet to be had. All you have to do is a little research.

We have written many articles about Jupiter for Universe Today. Here are some interesting facts about Jupiter, and here’s an article about the color of Jupiter.

If you’d like more information on Jupiter, check out Hubblesite’s News Releases about Jupiter, and here’s a link to NASA’s Solar System Exploration Guide to Jupiter.

We’ve also recorded an episode of Astronomy Cast just about Jupiter. Listen here, Episode 56: Jupiter.


What is Jupiter Made Of?

Of all the Jovian related questions that we get here at Universe Today, what is Jupiter made of is one of the most common. Jupiter is mainly composed of hydrogen and helium just like a star. Answering that question seems to open a flood of other questions about the gas giant, so here are some facts about Jupiter that should answer quite a few of them.

Jupiter does not have enough mass to ignite fusion and become a star like our Sun. Without that mass, Jupiter is also too cold for fusion. If Jupiter were to become 80 times more massive it would be able to generate enough heat for fusion through gravitational compression. Given that there isn’t that much mass in our Solar System, outside of the Sun, it is impossible for Jupiter to become a star. Can you imagine how scorched and barren all of the planets would be if ours was a binary star system?

Spectral analysis of Jupiter has revealed that in addition to hydrogen and helium, the planet is made of water, methane and ammonia. Those elements are in trace amounts. The core of the planet is thought to contain some rock and metallic hydrogen. Scientists estimate that the core is heated to 36,000 K. The planet is not just a ball of gas that you would be able to drop straight through. In addition to the rocky/molten metallic hydrogen core, there is a layer of liquid hydrogen and helium and areas where the hydrogen is in a supercritical state, meaning that it does not have distinct gas and liquid phases.

Another frequent question about Jupiter is about the ”stripes” that can be seen. Those stripes are actually an effect of the fast rotation of the planet. To be more specific, they are due to the combination of the planet’s rotation and that its gases are more intensely heated at the equator than the poles. This is similar to why the Earth has trade winds near the equator and jet streams near the poles…rising air interacts with the coriolis effect of the rotation and causes sideways deflections. Jupiter rotates much faster and has a thicker atmosphere, so its coriolis effect is much stronger, thus the stripes. Try this link for a more in depth explanation of the striations(stripes).

Just asking what is Jupiter made of only brings up a whole other set of questions. Be sure to keep looking and you will find plenty to stump your friends and teachers with.

We have written many articles about Jupiter for Universe Today. Here’s an article about the color of Jupiter, and here’s an article about the missions to Jupiter.

If you’d like more information on Jupiter, check out Hubblesite’s News Releases about Jupiter, and here’s a link to NASA’s Solar System Exploration Guide to Jupiter.

We’ve also recorded an episode of Astronomy Cast just about Jupiter. Listen here, Episode 56: Jupiter.