 Rather than list all the ranges of distances between the Earth and the various planets, a good way to report planetary distance is to use an average distance from the Sun. An astronomical unit, AU for short, is the average distance from the Earth to the Sun. That's 150 million kilometers or 93 million miles. We'll cover a way to measure AU in our segment on the Sun. Mars is one and a half AU, or 228 million kilometers from the Sun. That's 142 million miles. Mars has two small moons, Phobos and Deimos. The moons appear to have surface material similar to many asteroids in the outer asteroid belt, which we'll cover shortly. This leads most scientists to believe that both moons are captured asteroids. Here are the distances to the other planets in our solar system. Mercury, a hot, cracked rock not much bigger than the moon, is only 58 million kilometers from the Sun. That's 36 million miles. Its daytime surface temperature is 430 degrees Celsius. That's 800 degrees Fahrenheit. That's hot enough to melt lead. Mercury has no moons. Venus, with its sulfuric acid atmosphere, is 108 million kilometers from the Sun. That's 67 million miles. It's around 80% of the size of the Earth and as hot as Mercury. This ultraviolet view of the planet's clouds was taken by the pioneer Venus probe in 1979. The probe found that, like Mercury, Venus has no moons. Jupiter, the largest planet by far, is 778 million kilometers from the Sun. That's 483 million miles. Its mass is 317 times greater than the Earth. It is the giant solar system vacuum cleaner heating up the Sun's early debris to become larger than all the rest of the planet's combined. Scientists think Jupiter has at least 69 moons. The most interesting are the four discovered by Galileo. Ganymede, Callisto, Io, and Europa. Ganymede is the largest moon in the solar system and is the only moon known to have its own internally generated magnetic field. Callisto's surface is extremely heavily cratered and ancient, a visible record of events from the early history of the solar system. Io is the most volcanically active body in the solar system. As Io travels in its orbit, Jupiter's immense gravity causes huge tides in the solid surface like our moon affects the oceans. This generates the heat for the volcanic activity. Europa's surface is mostly water ice and there is evidence that it may be covering an ocean of water. It is thought to have twice as much water as we have here on Earth. This water, along with subterranean volcanoes, may have created a zone where life can form. Saturn, with its beautiful rings, is 1.4 billion kilometers from the Sun. That's 886 million miles. Its mass is 95 times greater than the Earth. The Cassini probe has been taking pictures of the planet, its rings and moons, for 13 years. Saturn has at least 62 moons and every one of them have been probed by the Cassini spacecraft. Here are two of them. Titan is the largest. It is the only moon in the solar system known to have a significant atmosphere. Enceletus has more than 100 water geysers at its south pole, from a subterranean ocean that may be friendly to life. Saturn's rings are absolutely beautiful. There are billions of particles in the entire ring system, ranging in size from tiny dust-sized icy grains to a few particles as large as mountains. It is about 1 kilometer thick and ranges out to 282,000 kilometers from the center of the planet. It's about three quarters the distance between the Earth and the moon. This Cassini image shows a portion of the inner central part of the planet's B-ring. Cassini ended its mission on September 17, 2017, with a plunge into Saturn's atmosphere. Uranus, with its extremely cold hydrogen and helium atmosphere, is 3 billion kilometers from the Sun, that's 1.8 billion miles. Its mass is 14 times greater than the Earth. Uranus has 27 known moons, the largest are Oberon and Titania. They were photographed by Voyager 2, the only spacecraft to ever visit Uranus. Neptune, a twin of Uranus, is the furthest planet from the Sun at 4.5 billion kilometers. It's 2.8 billion miles. It takes 164 years to revolve around the Sun. Neptune has 13 moons that we know of. Triton is the largest. It has ice volcanoes that sprout what is thought to be a mixture of liquid nitrogen, methane and dust, which instantly freezes and then snows back down to the surface.