The University of Texas at Arlington

The University of Texas at Arlington

UTA Planetarium

UTA Planetarium

Ask the Astronomer Q&A

Tag: "mars"

  • Have astronauts ever been to ___?
  • Astronauts have never been anywhere besides the Earth and Moon (but there have been no Moon trips since 1972). There are plans to return to the Moon (possibly by 2020) and then astronauts may travel to Mars. A trip to the Moon takes about three days, but a one-way trip to Mars will take close to nine months.

    (Tags:  astronaut  earth  mars  moon  nasa)
  • How long does it take to go to Mars?
  • The length of time it takes to go to Mars depends on how fast you are going and how far away Mars is from Earth. This distance changes due to the constant motion of Mars and Earth around the Sun. The average distance between Earth and Mars is about 46.5 million miles. If you traveled at freeway speeds, 60 miles per hour, it would take 88.5 years! If you are travelling at the speed of light (a speed we are incapable of achieving), it would take about 4 minutes to reach Mars. The fastest spacecraft that was ever launched into space, New Horizons, passed Mars in about 40 days on its way to Pluto. An average mission to Mars takes about 6 months to reach the red planet.

    (Tags:  mars  satellite  speed of light)
  • I am led to understand that the Earth has an atmosphere due to the fact we have a magnetic field that deflects the solar wind. It is further my understanding that Mars lost most of its atmosphere (and subsequently most of its water) because the core cooled and Mars lost its magnetic field. Why then does Venus have such a thick atmosphere given that it has no magnetic field combined with the fact that it is much closer to the sun and therefore is exposed to solar wind to a much higher degree than the Earth is?
  • Actually, Earth has an atmosphere because of the size of the planet. Since gravity is directly related to the size (mass) of an object, the larger it is, the more gravity it possesses. Earth’s gravity is able to hold on to the molecules that make up our atmosphere. Mars, being about ½ the size of Earth, has much less gravity. This allowed the atmosphere on Mars to “evaporate” away into space. Venus still has an atmosphere because it is very close in size to Earth, about 90% Earth’s mass.

    (Tags:  earth  gravity  mars  venus)
  • I know that Mars cannot hit Earth because it is so far away, but is there another reason why this is not scientifically possible?
  • Mars can never hit Earth because the two planets are in stable orbits around the Sun. The orbits do not intersect with each other, so there is no way the two objects could collide. But it is possible that Neptune and Pluto may someday collide with each other due to their intersecting orbits. We would need a catastrophic event to happen, like a star or black hole passing through our solar system, to change the orbits of the planets enough to cause Mars and Earth to collide.

    (Tags:  earth  mars  neptune  pluto)
  • I received an email saying that we will see Mars as big as the moon on August 27, 2010. Is this true?
  • No, this is not true. The emails started circulating in 2003 when Mars made its closest approach to Earth. It was closer than it had been in 60,000 years! But, because the distances between Mars and Earth is so great (at and average of 46.5 million miles away) and their size so small (Mars is only half the size of Earth), Mars can never look as large as the Moon. That year, it appeared as a very bright red dot in the sky. Mars is visible this month in the Western part of the sky after sunset. It will appear as a red dot low in the sky. If you want to read more about this email hoax and others we see, check out these great articles on our website!

    (Tags:  astronomy  earth  light  mars  moon  planet  solar system)
  • I was wondering if you could recommend a good telescope to get a better look at space. I don't mean a very expensive one, but a reasonable one to get a good look at the stars, planets.
  • If you are just beginning to use a telescope for enhancing your stargazing experience, we would recommend the Celestron FirstScope, which we have available in our gift shop for $60. This is a table-top telescope with a 3-inch diameter, perfect for viewing the planets and bright deep space objects, such as the Orion Nebula and the Andromeda Galaxy. This telescope is easy enough for children to use, but will last a long time. If you would like to get an intermediate or advanced telescope, I would recommend contacting the Texas Astronomical Society at They have a great online resource for finding the perfect telescope for your needs, and experts able to answer all your questions.

    (Tags:  astronomy  jupiter  mars  moon  planet  saturn  solar system  star  telescope)
  • If we suppose Jupiter has moved from the place that it was originally created to the spot it is now in our solar system, what affect would it's gravitational movement have on Earth?
  • The current model that astronomers use to explain how the solar system formed, does not include any changes in orbit after the planet forms. There may be slight adjustments to a planet’s orbit due to mass changes over time, but nothing that will explain back and forth movements of the planets, because that would require an external force. For Jupiter to move closer or farther away from the Sun, there would have to be an external force tugging it - allowing the orbital period to change. But there is no known source in the solar system that would have the power to change the orbits by that much. Even though the planets have a small gravitational effect on each other, a change in planet configuration wouldn’t cause a dramatic change to the orbits of the other planets. Most of the gravity in the solar system comes from the Sun, so as long as the Sun remains in the system, the orbits won’t change much (if at all). That’s why Earth and Mars don’t orbit around Jupiter when they get in conjunction with Jupiter.

    (Tags:  earth  gravity  jupiter  mars  solar system  sun)
  • What is the size and brightness of the Sun as viewed from the different planets in the Solar System?
  • We have a few simple calculations that you can use to find the size (in degrees) and the brightness of the Sun on each planet. In fact, these calculations will work for the brightness and size of the Sun from anywhere in the universe, as long as you know the distance of the object from the Sun in AU. To find the size of the Sun in degrees: a = 0.5/distance (in AU) where a is the size in degrees and 0.5 is the size of the Sun as seen from Earth. To find the brightness of the Sun as compared to its brightness as seen on Earth: M = 2.5 * log(distance)^2 – 26.74 Where M is the apparent magnitude of the Sun and 26.74 is the magnitude of the Sun as seen on Earth.

    (Tags:  earth  jupiter  mars  moon  planet  pluto  saturn  solar system  star  sun  venus)
  • Will NASA ever get to Mars knowing that it's so far away?
  • I think what you mean to ask is not whether NASA will get to Mars, but will NASA send astronauts to Mars, and I think the answer is yes. We have been sending robotic probes to Mars for decades. Several are on the surface testing the soil and sending beautiful panoramic images back to us on Earth. Others are in orbit, taking high resolution images of the surface from above. The problem with sending astronauts to Mars is that it would be a 1-3 year trip. It all depends on the technology we use and how close Mars and Earth are to each other in our orbits. NASA’s Constellation Program, which was started under the Bush Administration, was a project to take the best of the Apollo and space shuttle missions, and create a spacecraft that could return astronauts to the Moon, and maybe eventually to Mars or some near-Earth asteroids. But the project was over promised, and over budget, so it was removed from the NASA budget. But, the current NASA budget has money set aside for taking us to Mars or near-Earth asteroids, it is just hoping for some help from the commercial market. It may take 10-20 years for the new system to be developed, but we will get to Mars within our lifetime.

    (Tags:  asteroid  astronaut  earth  mars  moon  nasa)