Jupiter, Jupiter will be at opposition on August 19, meaning it will be visible whenever the sky is dark, peaking about midnight. The giant planet is located in the constellation Virgo (the Virgin). It's easy to find, as it lights up the entire horizon.
In fact, Jupiter is the only object that can be seen from anywhere on Earth at night. It's always been important to astronomers because of its huge size compared to the other planets: it fills half of the sky when it reaches its greatest distance from the Sun.
Astronomers use telescopes to see things on distant planets and stars that are too small or far away to be seen with the unaided eye. By studying these objects across many nights they learn more about their own planet and the other objects in the Solar System.
Currently, there are two ways to see Jupiter with your naked eye: either look towards the Bear Star (Ursa Major) or out towards the Summer Triangle (Beta Lyrae, Altair, and Vega).
However, neither of these are easily visible from most parts of the world. The best place to see Jupiter may be from within a dark site where you can watch it move across the face of the moon.
Jupiter will be at opposition on August 19, meaning it will be visible whenever the sky is dark, peaking about midnight. It currently burns directly on the Capricorn-Aquarius equinox, and appears early in the evening twilight, but it's still somewhat low in the southeast.
Jupiter is the largest planet in our solar system and by far the most massive body beyond the Earth's core. It has been estimated to contain more than 17% of the total mass of the Sun. Although similar in size to Earth, Jupiter is over 93 million miles away from us. It takes 12 years to orbit the Sun, so you can see all nine planets in the Solar System every twelve years or so if you're able to keep track of them across the night sky.
When viewing Jupiter through a telescope, there are two things to consider: magnification and perspective. When you look up at the night sky through a small telescope, even a large one, you are looking at the surface of Jupiter at a great distance. This makes its features seem smaller than they actually are. The exception is when it is near opposition, when it becomes larger than any other object in the sky. Even with high magnification, you cannot see the surface detail of Jupiter.
Jupiter has four major natural satellites: Io, Ganymede, Europa, and Callisto.
This massive planet has a strong magnitude of 2.9.
To see Jupiter, you need a telescope or good eye: it is over 100 million kilometers from Earth, so its image on the retina fills your vision. But even without a telescope, you can see some detail of its four largest moons: Io, Ganymede, Callisto, and Europa. They are all huge bodies covered with features that seem to match those on Earth, from volcanoes to ravines.
Io is the most volcanically active body in our solar system. The sulfur dioxide gas it produces causes hazes that block out parts of Jupiter. Galileo saw hundreds of volcanic eruptions during his first close-up look at Jupiter in 1610. Since then astronomers have discovered more than 700 active volcanoes on Io.
Ganymede is the largest moon in the Jovian system and also the only one that doesn't seem to be locked into orbit around Jupiter. It orbits Jupiter every 8 days, but that's much closer in than any other moon. That means that every time Ganymede passes over a region of the planet's surface, it sweeps away any material it contains.