Jupiter: how to see bright this week, what does opposition mean - and how to see Jupiter’s moons and Saturn

The solar system’s biggest planet will appear bright in the night sky this week - here’s how to spot it with your own eyes

Stargazers and astronomy buffs will want to look to the heavens this week, as Jupiter is set to put on a dazzling show in the night sky.

The mighty gas giant planet will appear to the naked eye as “a bright star, though it won’t twinkle like the stars”, because it will be at “opposition”.

But what exactly does that mean? And what’s the best way to catch a glimpse of Jupiter this week?

Here is everything you need to know about it.

What does ‘opposition’ mean?

Opposition - when applied to celestial bodies like planets, means that as Earth passes between the Sun and Jupiter, the planet will appear opposite the Sun.

Bryony Lanigan, an astronomer at the Royal Observatory Greenwich, said: “When a planet is at opposition, it is on the opposite side of the Earth to the Sun – if you were looking down on the Solar System from above and drew a line from Jupiter to the Sun, when Jupiter is at opposition it would pass through the Earth.

“This doesn’t necessarily mean that the planet is at its closest point to the Earth – because of the elliptical nature of planetary orbits, this may occur a day or two either side.”

Lanigan added that planets are usually in opposition for a very short length of time but, during that time, they are visible to the naked eye.

When can I see it?

Jupiter will be at its brightest on the evening of Thursday 19 August, and the planet’s opposition takes place just days before the full moon on 22 August.

Lanigan added: “While the sky will not be fully dark, the Moon will not be intruding too much on astrophotographers’ views.”

Jupiter should be visible low above the south-eastern horizon from sunset on the days around opposition on 19 August, but if you wait until a few hours after sunset then it will have risen higher – around 20-25 degrees altitude – and will be easier to spot.

What else can I see?

To those with telescopes, the Galilean moons (including Ganymede, pictured here) will look like ‘pinpricks of light’ in orbit around Jupiter (Photo: NASA/Newsmakers)

Those looking for Jupiter in the night sky may catch a glimpse of Saturn as well.

Ed Bloomer, also a Royal Observatory Greenwich astronomer, said: “Both planets are fairly low on the horizon, so try and find an observation spot free from tall buildings or trees when looking in that direction.

“And another bonus is that the waxing moon is – relative to the planets – sweeping eastwards over those few days.

“There’s a chance you could get a good photograph featuring stars, planets and the Moon.”

Those looking through telescopes may catch a glimpse of Jupiter’s moons as well as Saturn’s rings.

Bloomer added: “The Galilean moons (Jupiter’s four largest moons – Io, Europa, Ganymede, and Callisto) will look like pinpricks of light in orbit around Jupiter.

“Around Saturn you may be able to make out the rings, and even major divisions within the rings. If your telescope is really good, perhaps you’ll even make out the swirling clouds of Jupiter’s upper atmosphere.”

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