Night sky highlights - June 2017

ROG Opening Times

Important Notice for the 31 December: The Royal Observatory North (Flamsteed House) and Meridian Line will open to the public at the later time of 11:30. The Astronomy Centre and Planetarium will open as normal at 10:00.

This month, have a look for the stars of the Summer Triangle : Vega, Deneb and Altair.

(Details given are for London and may vary for other parts of the UK.)


The Moon is primed for viewing at the beginning of the month, starting with a First Quarter on the first and growing to a Full Moon by the 9th. This is the best time to look at the Moon through binoculars or a telescope because long shadows along the Terminator – the line separating light from dark on the Moon – will help you pick out mountains and craters. Over 400 years ago Galileo used the length of these shadows to estimate the height of lunar mountain ranges.

Now we’re into the summer months, the famous Summer Triangle is clearly visible in the sky once again. This is not a constellation. Instead, it is made from the brightest three stars in the three constellations of Cygnus, Lyra and Aquila. Deneb sits at the tail of Cygnus (The Swan), but the constellation’s most spectacular star is Albireo at the bird’s beak. Through a pair of binoculars you’ll see that it is not one star but two, one golden yellow and the other electric blue. The reason for their different colours is that they have difference surface temperatures. Blue stars are much hotter than yellow stars.

Just to the left of Altair at the bottom of the triangle is a rather unspectacular constellation called Delphinus the Dolphin. But it is interesting for two reasons. First, as a relatively faint constellation it is an excellent test of light pollution. If you can see it with your own eyes then your light pollution levels are low. However, the best thing about Delphinus is the names of two of its stars: Sualocin and Rotanev. You have to know that as astronomers it is against the rules to name stars after yourself. However, the names of these two stars backwards spell out Nicolaus Venator – the former director of the Palermo Observatory in Sicily, Italy who found a way to bend the rules!

When it comes to planets, Venus, Jupiter and Saturn are the easiest to see this month. Jupiter shines brightly in the constellation of Virgo close its brightest star Spica. It is joined by the Moon on the 3rd. By the 9th, the Moon has moved round the sky and sits just about Saturn in the South-East before midnight. Venus is visible in the pre-dawn sky dazzling in the East not far from the famous group of stars known as The Pleaides or Seven Sisters. It reaches Greatest Elongation on the 3rd, meaning that it is a far from the Sun as it gets from our perspective.


Get prepared for stargazing

When looking at faint objects such as stars, nebulae, the Milky Way and other galaxies it is important to allow your eyes to adapt to the dark – so that you achieve night vision. Allow 15 minutes for your eyes to become sensitive in the dark and remember not to look at your mobile phone or any other bright device when stargazing. If you are using a star app on your phone switch on the red night vision mode.

Need a stargazing telescope or decent binoculars? Check out our range of high-quality observing equipment recommended by Royal Observatory astronomers:

See our range of observing equipment

Share your astronomy pictures

Don’t forget to share your pictures of the night sky with us on Twitter @ROGAstronomers or via Facebook

Come and see last year’s amazing entries to the world’s biggest astrophotography competition (Insight Astronomy Photographer of the Year) in our free exhibition at the Royal Observatory.

Visit the free Insight Astronomy Photographer of the Year exhibition

See more of the night sky

Come on an amazing tour of this month’s night sky in our Sky Tonight live planetarium show

See the Sky Tonight planetarium show