Set your alarm for the early hours of 17 June to catch five planets meeting in an alignment in the sky – here’s everything you need to know.
Which planets will be visible?
On 17 June 2023, Mercury, Uranus, Jupiter, Neptune and Saturn will all appear together in the sky. Jupiter and Saturn will be easy to spot with the naked eye, but while it should be possible but trickier to see Mercury, you will need to get some binoculars or a small telescope to find Neptune and Uranus.
How can I see the alignment?
The best opportunity is in the southern hemisphere, where it is currently winter and the longer hours of darkness mean there will be more time to spot all five planets. They will rise in the following order: Saturn, Neptune, Jupiter, Uranus and, finally, Mercury.
All five planets will be visible just before sunrise on 17 June. Saturn and Jupiter will be shining brightly above the horizon, with Saturn highest in the sky in the north about two hours before sunrise. Despite being the last planet to rise, you will still have almost two hours to catch Mercury before the sun comes up.
Grab your binoculars and look between Saturn and Jupiter to find Neptune. It will be sitting directly between the two larger planets, about a third of the way from Saturn towards Jupiter. Through binoculars or a small telescope, it should have a slightly blue tinge.
Uranus will appear closer to the horizon, making it harder to find. It will be on the other side of Jupiter from Neptune. To look for its position, you can use a free stargazing app such as SkyView Lite, available on iOS or Android, or software like Stellarium on a PC.
Be careful when using binoculars close to sunrise, and remember never to look at or near the sun through them.
What about in the northern hemisphere?
With fewer hours of darkness, finding all the planets means getting up about an hour before your local sunrise time. Jupiter and Saturn will be bright in the south-eastern sky, with Saturn further towards the south and slightly higher in the sky. Jupiter will be directly above the eastern horizon an hour before the sun comes up. You will have less time to spot Mercury, as it will rise at around half an hour before sunrise.
How can I tell whether I’m looking at planets or stars?
The general rule is that stars twinkle, planets don’t. The light from stars comes from so far away that it acts like a point source, similar to a laser beam. This means that, when compared with the light from planets, starlight is more susceptible to distortions in its direction when it enters our atmosphere. These distortions cause the apparent twinkle.
What causes a planetary alignment?
If you were to look down at our solar system from above during this alignment, the planets wouldn’t be in a straight line. Instead, they are all on the opposite side of the sun to Earth, meaning they reflect their light back towards us. This is what gives the planets the appearance of sitting in a line when viewed from here on Earth.
How often do they occur?
These alignments depend on the movements of all the planets involved, so there is no regular pattern to them. Last June, we had an alignment of Mercury, Venus, Mars, Jupiter and Saturn, and the last time those planets appeared in a line before that was 2016.