Starwatch: Jupiter in opposition

Star chart Mon 7 May 2018

The giant gas planet Jupiter reaches its closest point to Earth this year on 9 May. A planet beyond Earth’s orbit, such as Jupiter, is known as a superior planet, and the closest approach of a superior planet is called opposition. This is because the sun is always 180° away from the planet at the moment of its closest approach. In effect, the sun, Earth and the planet in question all line up with Earth in the middle. Jupiter is the largest planet in the solar system and takes almost a dozen years to orbit the sun. Earth travels faster on its shorter orbit, catching up with Jupiter and creating an opposition every 399 days. On 9 May, Jupiter will be 5.4 times further from the sun than Earth, meaning it will be 6.6m kilometres (4m miles) away. At opposition, Jupiter is brighter than at any other time. This year, the planet will lie in the constellation of Libra. The chart shows its position at 00.00 BST on 9 May.