How you can see Jupiter in opposition tonight © Getty Images

How you can see Jupiter in opposition tonight

Tonight, 19 August, is your best opportunity to see the king of the Solar System – no telescope required.

August is quite often one of the quieter months in the astronomical calendar. With the Sun setting later through the summer months, it can make fainter objects challenging to observe.

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The plus side is that warm weather makes it the perfect time for beginners to get to know the night sky without winter coats and woolly hats, however.

A particular gem is the king of the Solar System: Jupiter, which comes into opposition on 19 August.

As the outer planets orbit around the Sun, Earth occasionally finds itself between the Sun and another planet, with all three in direct alignment. When this happens, we describe it as a planet being in opposition.

Oppositions occur roughly annually (with Mars being the exception, at 27 months) and can often provide the best opportunity to observe and photograph the particular planet because of its favourable position and brightness.

At Jupiter’s opposition, Earth will lie directly in between Jupiter and the Sun. It will appear bigger and brighter than usual as it’s also when Earth and Jupiter’s orbits are closest together (known as perigee).

Diagram showing where Jupiter will appear in the sky at 1:20am on 20 August 2021 © Pete Lawrence
Looking south at 1:20am BST on 20 August © Pete Lawrence

From around 9:14pm, Jupiter will begin to rise in the eastern constellation of Capricorn, just 7° above the horizon. As the night progresses, it will climb until it reaches its highest point, 24° above the horizon at 12:20am (so you won’t need to stay up too late to enjoy it).

As dawn approaches, it will slowly descend, disappearing below the horizon at approximately 4:56am.

For naked-eye observers, Jupiter will appear as a very bright point of light that, unlike stars, does not twinkle. A decent set of binoculars (7×10 magnification) will provide you with a view of Jupiter’s four largest moons, Ganymede, Europa, Callisto and Io, and a telescope will allow you to view Jupiter’s stripes.

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