Mars has two moons: Phobos and Deimos. They’re unusual, compared to other planet’s satellites, because they’re so tiny and orbit so close to the planet. The larger of the two, Phobos, is shaped something like a potato and has a diameter of anything from 20 km to 28 km, depending on how you measure it. It orbits at an altitude of only 9,270 km (compared to Earth’s moon, at over 350,000 km!). Although Deimos orbits at a more reasonable distance … Continue reading →
William Herschel discovered Uranus, and it was completely by accident. In 1781, while using one of his powerful home-made telescopes to survey a region of the sky in the constellation Taurus, he noticed that one star seemed a little larger than the rest. When he checked up on it again a few days later, he found that it had moved which helped confirm that it was actually a new planet. Although he tried to name it after his King, George … Continue reading →
Well now that depends on what you’re measuring from! Let’s try some possibilities: How far is Mars from the Sun? On average: 227.92 million kilometers. But, like everything else in the universe, Mars does not have a perfectly circular orbit. Instead, it moves in an ellipse, sometimes getting as far out as 249.23 million kilometers, and sometimes as close as 206.62 million kilometers. How far is Mars from the Earth? Anything from 54.52 million kilometers up to 401.33 million kilometers. … Continue reading →
Venus has no moons. Zero. Zip. This is quite unusual in our Solar System, as even the larger asteroids tend to have moons. The fact that we have satellites in permanent orbit which have not spotted any satellites means that we can be sure that Venus’s moons definitely do not exist. Comments? Questions? Why not mail me at uastronomer@gmail.com
Continue reading →Twenty three. When Galileo first saw Saturn‘s rings, his telescope was primitive enough that he could only see that there was something odd about Saturn’s shape. As time passed, and more astronomers used better telescopes to observe Saturn, a clearer and clear picture emerged. First it became clear that the mystery shape was a gigantic ring around the planet. Then a gap was noticed – the Cassini Division – increasing the count to two rings, followed by more gaps, and … Continue reading →
