Alert – Jupiter At Closest Approach To Earth
Jupiter from Juno. Credit: NASA/JPL-Caltech

Alert – Jupiter At Closest Approach To Earth

08/05/2018Written by Tamela Maciel

Excellent viewing of Jupiter this week as it reaches opposition.

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Jupiter at Opposition

Jupiter at Opposition
Credit: Tamela Maciel (author)

Look to the skies this week – Jupiter is looking its absolute best and brightest, and visible all night long.

On 9 May 2018 at 1:28 BST, Jupiter will line up with the Sun and the Earth, with the Earth in the middle. This phenomenon is known as ‘opposition’ (literally Jupiter will be opposite the Sun in the sky).

This alignment means that Jupiter will be closer to Earth than at any other time in the year. It will be fully lit up from the light of the Sun, similar to a full Moon, making it appear big and bright in the night sky.

How to view

How to view
Jupiter at 10pm on 9 May 2018. Credit: Stellarium
How to view
Jupiter's four largest moons at 10pm on 9 May 2018. Credit: Stellarium

To the naked eye, Jupiter will appear as an exceptionally bright dot in the sky which rises in the east just past 21:00 BST in the evening and sets in the west at 4:30 BST in the morning.

It will reach its highest point in the southern sky at 00:57 BST. A stargazing app or chart for May may be helpful to locate Jupiter, but really just look for an exceptionally bright dot in the southern-eastern sky after sunset.

With a good pair of binoculars, you should be able to see Jupiter’s four largest moons – Ganymede, Callisto, Europa, and Io – as four small dots on either side of the planet.

With a medium-sized telescope, you’ll be able to see the four moons as well as some of the faint striped clouds of Jupiter’s atmosphere.

Here in the UK, we’ve been blessed with remarkably clear nights recently, but if clouds prevent you from seeing Jupiter tonight, then be sure to look for it another night over the next few weeks. It will still appear as a bright object in the evening sky.

While you’re outside in the evening, also look west for Venus. This planet will be setting in the western sky just after sunset.


Jupiter's northern aurora. Credit: NASA, ESA, and J. Nichols (University of Leicester)
Juno at Jupiter, artist impression. Credit: NASA

Jupiter is the fifth planet from the Sun and the largest of the gas giant planets. It’s 778 million kilometres from the Sun, and you could fit 1,300 Earths inside it!

As a gas giant, Jupiter lacks a solid surface. Its clouds are mostly hydrogen and helium gas, with swirling clouds and storms that give it its distinctive stripes.

Jupiter’s most famous storm is the Great Red Spot, a giant oval of crimson-coloured clouds in Jupiter’s southern hemisphere with wind speeds greater than any storm on Earth. Measuring 16,000 kilometres across, the Great Red Spot is 1.3 times as wide as Earth.

Jupiter also has some striking aurora (northern lights) at its north and south poles. These purple & UV lights are caused by wind from the Sun striking Jupiter’s strong magnetic field. Scientists at the University of Leicester are experts in studying these aurora on Jupiter and what causes them.

Jupiter rotates once about every 10 hours (amazingly fast for such a large planet), but takes about 12 Earth years to complete one orbit of the Sun.

This king of the planets is circled by 69 known Moons, including the famous Galilean moons – Ganymede, Callisto, Europa, and Io – first discovered in 1610 by Galileo Galilei.

Currently, Jupiter is being explored by the spacecraft Juno, which has been in orbit since July 2016.

Jupiter isn’t the only planet to reach opposition – in the coming months we’ll also see close approaches from Saturn (on 27 June 2018) and Mars (on 27 July 2018).

Clear skies!

About the author: Dr Tamela Maciel is the Space Communications Manager at the National Space Centre.