The University of Texas at Arlington

The University of Texas at Arlington

UTA Planetarium

UTA Planetarium

Ask the Astronomer Q&A

Tag: "jupiter"

  • Can we make Jupiter, Saturn, Uranus or Neptune into mini-Suns using lasers to ignite the fusion process, like they do at the National Ignition Facility? If so, will their moons begin to rotate instead of being tidally locked?
  • Your question is an interesting one. However, I must say that there is no way to turn these planets into mini-Suns by sending laser beams. Here are several major problems with your suggestion. First, laser beams would be damped in atmospheres of these planets and the beams would never reach central parts of the planets. Second, lasers beams are highly collimated, which means that we could only trigger a fusion process very locally in the upper parts of the planetary atmospheres, where gas density and temperature are relatively low. Third, the fusion process (if ever triggered) would neither be sustained nor spread throughout the atmosphere. Fourth, neither of these planets would be able to sustain nuclear reactions in their interiors (even if we found a way to ignite them there) because the interior temperatures and densities in these planets are not high enough to initiate any fusion process. Finally, I do not think that our current lasers are strong enough to even trigger a very localized fusion process in the most upper parts of atmospheres of these planets. Now, the fact that the moons are tidally locked has to do with the planet’s gravity, which would not change whether nuclear reactions would occur or not.

    (Tags:  gravity  jupiter  laser  light  neptune  planet  saturn  sun  uranus)
  • Gliese 710, an Orange dwarf star, will be headed our way in 1.5 million years. Gliese 710 is expected to come within 1.1 light years of our Solar System, perturbing the Oort Clouds and its comets. Can it grab some of the moons of the giant gas planets (Jupiter, etc) and make them satellites for itself, re-arranging our Solar System?
  • It is not likely that Gliese 710 will have any effect on the moons of the gas giant planets because 1.1 light years is still a very long way away. For reference, the Sun is about 8 light minutes away from Earth. Pluto is about 5.6 light hours away from the Sun. At 1.1 light years away, Gliese will be over 5 trillion miles from the solar system. This may be close enough for the star’s gravity to have an effect on the edge of the Oort Cloud, as you mentioned, but this will likely mean an increase in meteor showers and comets. It would not completely rearrange our solar system.

    (Tags:  brown dwarf  earth  gravity  jupiter  meteor  planet  pluto  saturn  solar system)
  • How many planets have rings?
  • All the gas giant planets - Jupiter, Saturn, Uranus and Neptune - in our solar system have rings, but only Saturn's are bright enough to see from ground based telescopes. Although astronomers have not yet detected rings around planets orbiting other stars, it is likely that they do exist outside of our solar system as well.

    (Tags:  exoplanet  jupiter  neptune  planet  saturn  solar system  uranus)
  • 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)
  • I've heard people say Jupiter is a failed star since its made up of mostly Hydrogen and Helium like a star is. I know a Brown Dwarf is essentially a failed star, so would that make it correct to think of Jupiter as a Brown Dwarf? If not, why?
  • Jupiter is not a failed star or a Brown Dwarf. It is a gas giant planet. Brown Dwarfs are objects that are between 10 and 100 times more massive than Jupiter. They are not large enough to sustain Hydrogen fusion in the cores, this is why they are sometimes called failed stars. In order for Jupiter to be considered a Brown Dwarf it would need to get at least 10 times more mass than it currently has.

    (Tags:  brown dwarf  hydrogen  jupiter  star)
  • If I were to fast-forward into the future, and I was setting up a base on Callisto, what might be the best place to do that? Would somewhere like in the Lofn crater be a good place to put it? If so, what would the area look like? Would I be able to see Jupiter from there? Would the ground feel and look like snow? Would the thin atmosphere carry any sort of sound?
  • Callisto is a tidally locked moon which means that the same side is always facing Jupiter (like our Moon). Unfortunately, the Lofn crater is located on the far side the moon (56˚ S and 23˚W) so your base would never see Jupiter. The surface of Callisto is covered by ice (water ice), carbon-dioxide and silicates; so it wouldn’t feel like snow, it would feel like hard ice. The thin atmosphere is so tiny; you can almost consider there is no atmosphere. It is surprising that this tiny moon has an atmosphere; however, it is not stable. The atmosphere is actually running away and is probably being replenished by the surface carbon-dioxide. Such an atmosphere wouldn’t carry any sound.

    (Tags:  jupiter  moon  physics  solar system)
  • If Jupiter had developed into a brown dwarf star what effects would that have had on Earth's development? How visible would Jupiter be during the day and at night as a star?
  • If Jupiter was a brown dwarf star, it would not affect Earth very much. Brown dwarfs do not create much light, and since Jupiter is an average of 5 AU from the Earth (5 times the distance between the Earth and the Sun) it would appear as a pinpoint of light, a little brighter than Venus in the night sky. The farther away from the object you get, the dimmer and smaller it appears in the sky. For example, if we were to travel to Pluto, there would be no daytime. The Sun appears as a very bright star compared to the other stars in the night sky. But because it is so far away, it does not cast enough light on Pluto’s surface to have a bright daytime sky.

    (Tags:  brown dwarf  jupiter  pluto  star  sun)
  • If Jupiter has no solid surface why were we able to witness the impact of the comet Shoemaker-Levy and it's apparent scars after the collision, why didn't the comet just get absorbed within the planets depths?
  • When comet Shoemaker-Levy collided with Jupiter, it ionized due to the intense pressure and speed of collision. Those ionized particles mixed with the gases in Jupiter’s upper atmosphere, which is what we were able to see as “scars” on Jupiter. After several days the particles settled towards the core of the planet and they were no longer visible.

    (Tags:  comet  jupiter)
  • 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)
  • Is it possible that the gas giant planets are just planets that haven't fully formed yet? Like gravity hasn't fully brought them together and compressed them to a solid yet?
  • The gas giant planets are fully formed planets. They just don’t have solid ground. But they definitely have gravity. Everything that has mass, has gravity. The more massive an object, the more gravity it has. And the gas giants have A LOT of mass. Jupiter, for example, is 318 times more massive than Earth and has 2.5 times more gravity than Earth. This incredible amount of gravity holds the planet together and compresses the gas into a liquid closer to the center.

    (Tags:  gravity  jupiter  neptune  planet  saturn  uranus)
  • Is it safe to look at Jupiter through a big telescope this month, September 2010?
  • Absolutely! Jupiter is currently near opposition. It is the best time to see Jupiter and the Galilean moons Io, Europa, Ganymede, and Callisto. Unlike the Sun, it is always safe to look at planets with telescopes. To look at the Sun, specially designed filters that take 99.9% of light away must be used. Otherwise permanent damage to the eye will occur. It is even harmful to look at the Sun directly (with unaided eye).

    (Tags:  jupiter  light  planet  solar system  sun  telescope)
  • Is Jupiter a "brown dwarf" star?
  • No. A brown dwarf is a kind of star. For Jupiter to exhibit any resemblance to a star it would have to fuse lighter elements into heavier ones in the core. An object needs to be about 80 times more massive than Jupiter for this to occur.

    (Tags:  brown dwarf  jupiter  planet  star)
  • What is the average number of planets that orbit a star?
  • In most cases, only one planet is discovered around stars that are known to host planets. There are a few stars where second, third and fourth planets have been discovered. With numbers, there are 334 planetary systems discovered with a total of 394 planets as of today. Out of 334, only 41 systems are multi-planet systems. Discovery of a planet system like our solar system is has not been made yet; however, this does not indicate the Solar System is unique. Discovery of smaller planets is an extremely difficult task. For example, if we were looking to the Solar System from a nearby star, we probably would not discover smaller planets in the first place, and think the Sun has 2 planets; Jupiter and Saturn.

    (Tags:  jupiter  planet  saturn  solar system  star  sun)
  • What is the largest planet of the solar system?
  • The largest planet is Jupiter. It is so large, that we could fit 1000 Earth's inside of it. However, compared to the Sun, Jupiter is very small. We could fit 1000 Jupiter's inside the Sun.

    (Tags:  earth  jupiter  planet  solar system  sun)
  • What is the possibility of dropping U-238 into Jupiter, for example, to trigger the proton-proton chain reaction? Or, the CNO cycle (carbon-nitrogen-oxygen) to turn all the gas giants into mini-Suns? After all, U-238 has a half life of 4.5 Billion years, and we have a surplus of U-238!
  • Although it may allow us to get rid of our Uranium, this wouldn't work to create another Sun. Atoms bombs like those made with U-238 create fission reactions, which are the opposite of fusion reactions. In fission, you are breaking apart an atom and creating smaller ones – and a lot of energy! In fusion, like within a star, 2 small atoms are joining together to make a larger atom – and again a lot of energy. So, sending our atom bombs to Jupiter would only blow it up, not start a fusion reaction. The only way to start a fusion reaction is to add more mass. To make Jupiter into a small brown dwarf star, we would need to add about 9 more Jupiter’s worth of Hydrogen to the planet. To make a Sun-sized star out of Jupiter, we would have to add 100 more Jupiter’s worth of Hydrogen. That’s a lot of Hydrogen!

    (Tags:  brown dwarf  hydrogen  jupiter  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)