Jupiter, the giant planet of the Solar System, is putting on its best show this month by shining brilliantly all night long. And you don’t need a telescope to see Jupiter shining at its best!
Jupiter is currently on the opposite side of the sky to the Sun, as viewed from Earth. It rises about the time it gets dark and then crosses the sky to set around dawn.
The actual date of opposition occurred on April 7, 2017, and in the coming weeks Jupiter will dominate the evening sky, making it possible for amateur astronomers to observe it at a convenient time.
By the end of April, Jupiter will be rising about two hours earlier than it did at the start of the month, due to the change in geometry as the Earth orbits the Sun,
No telescope or binoculars are needed to see Jupiter, of course, because it is the brightest object in the night sky after the Moon and our inner neighbour Venus (which is now a pre-dawn sight).
You really can’t miss Jupiter shining at its best – unless it is cloudy, of course! You will easily find it shining brilliantly at magnitude -2.5 (in the magnitude scale used by astronomers to describe brightness, the bigger the number, the fainter the object).
It lies just south of the celestial equator, in the constellation of Virgo, not far from its brightest star Spica. You may have noticed that it was also close to the Moon on the nights of April 10 and 11. They will come close together in the sky again on the May 7.
Though Jupiter is a great sight with just the eyes alone, also making a great photo opportunity for your camera, you will see much more if you have a telescope. Even a small instrument will reveal four starlike points to either side of the planet. These are the Galilean Moons, so-named because Galileo was the first user of an early telescope to remark upon them.
They are bright enough to be seen with binoculars, looking strung out like bright beads. Their positions vary as they orbit Jupiter so you might spot two on each side of the planet one night, then all on the same side another. Sometimes fewer than four will be visible if one or more happen to be behind or in front of Jupiter at the time.
In order from the planet, the Galilean moons are Io, Europa, Ganymede and Callisto. Jupiter has actually had 67 satellites discovered by 2017, but these four are the only ones of significant size. Ganymede is the largest moon in the Solar System and is bigger than planet Mercury.
Even binoculars will show that Jupiter is a disk, and this can be more clearly seen with a telescope. A small telescope is enough to reveal that the disk is not circular but is slightly squashed. Jupiter spins as a rapid rate, once in less than 10 hours, which causes the gas ball to bulge at its equator.
It will also become almost immediately obvious that there are shaded bands on Jupiter. They are more subtle than might be suggested by enhanced photos taken of the planet, but if you spend time letting your eyes adjust, you should see these delicate patterns. With a larger telescope, may also see the famous Great Red Spot,which is a raging cyclone in Jupiter’s cloud tops.
The different bands are known as belts or zones and are given individual labels, such as the North Tropical Zone and the South Equatorial Belt. The zones are bright and are where Jupiter’s weather systems move from west to east. Dark belts have their prevailing winds blowing in the opposite direction, from east to west.
The amount of detail you see on Jupiter will depend partly on the size and quality of your telescope, but also the amount of turbulence in our own atmosphere. This effect is known to astronomers as the “seeing conditions”.
Amateur astronomers equipped with CCD cameras are today able to take images of Jupiter that show a remarkable amount of detail in Jupiter’s belts and bands. This ability is due to a technique where individual frames can be combined and then enhanced with image-processing software like Photoshop.
Whatever equipment you have, or even if you have none, do take time to seek out Jupiter shining at its best. It is an awe-inspiring sight to observe our Solar System’s premier world.