Universe Today

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.