The best of astronomy this month: See the total lunar eclipse and Mars at opposition on 27th July.
By Dhara Patel, Astronomy Education Officer
(Details given are for London and may vary for other parts of the UK).
Top 3 things to see this month:
19th Jul - Spot the first quarter moon, Jupiter and the star Spica in the south-west before midnight.
27th Jul - Look for Mars as it reaches opposition.
27th Jul - Catch the total lunar eclipse in the south-east in the early evening.
Look Up! Podcast
As well as taking you through what to see in the night sky each month, Royal Observatory Greenwich astronomers pick their favourite astro news story. For July, they're chatting about Mars - the latest revelations and the Opportunity rover braving a dust storm as well as new evidence for a rare type of black hole discovered in the outskirts of a distant galaxy. Have a listen below then vote for your favourite news story on our Twitter poll during the first week of the month.
Our podcast is now available on iTunes too - search Look Up and rate us if you enjoyed listening!
Throughout the month look towards the west after the setting Sun and you’ll find the planet Venus, the roman goddess of love, hanging bright in the sky. On the evening of 9th July, Venus will be close beside the star Regulus – only 1o apart in the sky (that’s about the width of your little finger held out at arm’s length)! This blue-white coloured star rotates much faster than it should - spinning only 15% below the speed at which it would fly apart. Its rapid rotation means that Regulus bulges out around its centre and is more of an oblate / egg-shape than a sphere. And if you wait until the 15th, you’ll also be able to catch the thin waxing crescent moon in the frame with this pair.
Although July isn’t a favourable month to catch meteors, there are several meteor showers that are beginning to become active which then peak at the end of the month or in August. The Alpha Capricornid meteor shower is active between Jul 11th and Aug 10th and the Delta Aquariid shower becomes active around 21st July up to 23rd August. Both showers peak around the end of the month (27th – 29th July) but are very weak. You may still be able to catch the very bright fireballs – look towards the south after midnight where the radiants of these shower will appear in the constellations of Capricornus and the neighbouring Aquarius. The Perseids meteor shower (a more impressive display) also becomes active from 13th July but doesn’t peak until August.
By 19th July the first quarter moon will appear close to another one of the naked-eye planets - Jupiter and will be even closer to the brightest star in the constellation of Virgo called Spica! Look to the south-west before midnight to see the trio of objects. The Moon does appear to move quite quickly across the sky from night to night and will be closer to Jupiter on the following night. However Jupiter will remain in the south-west throughout the month and is a fantastic target for any evening.
The quarter phases of the Moon are a great opportunity to spot craters. The terminator which is the boundary between the light and dark parts of the Moon is where the craters appear more prominent due to the shadows cast by the crater walls. If you have a pair of binoculars of a telescope you might want to get them out to take a closer look at these features!
Although Mars is a planet visible to the naked eye, it is normally quite faint. However, on the early morning of 27th July, Mars reaches opposition. It will be below the horizon when it reaches the exact moment but you can catch it just before in the hours after midnight looking towards the south. This is when Mars is on the opposite side of the Earth compared to the Sun. The alignment of these bodies during opposition means that Mars is at its closest position to the Earth and so appears much brighter. The opposition this year is quite favourable too as Mars is also particularly close to the Sun in its elliptical orbit meaning Mars will be even brighter than Jupiter. It will still appear as a star-like point of light so you’d need a telescope to distinguish its shape and other features. You can spot Mars throughout the month but it will only be considerably brighter for a few weeks on either side of this date.
By chance, there is also a total lunar eclipse on 27th July. The full moon will pass into the Earth’s shadow where sunlight would normally be unable to reach it. However the Earth’s atmosphere scatters or ‘bends’ the Sun’s light, such that the long wavelength red light is ‘bent’ by just the right amount that it illuminates the Moon giving it a reddish hue. Unfortunately, the Moon will have already begun to pass into the Earth’s shadow when it’s still below the horizon for UK viewers so when it rises it will already appear a red colour. The maximum eclipse (when the Moon is closest to the centre of the Earth’s shadow) occurs at 9:21 pm local time when the Moon will be low in the south eastern sky. Close to midnight the Moon will be leaving the Earth’s shadow and will have lost its red colour; by then Mars will be clearly visible to catch in all its glory!
The Moon's phases this month
- 6 Jul - last quarter moon (7:51am)
- 13 Jul - new moon (2:48am)
- 19 Jul - first quarter moon (7:52pm)
- 27 Jul - full moon (8:20pm)
See the other incredible photographs from the 2017 Insight Astronomy Photographer of the Year competition in our free exhibition like Evening in the Ptolemaeus chain and Rupes Recta region by Jordi Delpeix Borrell which was runner up for Our Moon category
The exhibition is open until 22 July 2018.
- 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 can achieve better 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’re using a star app on your phone then 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:
Share your astronomy pictures
Congratulations to Shawna Cadwell for her stunning image of the night sky. She shared her image on our astrophotography Facebook page and we chose it for July's banner image.
If you want to be in with a chance to showcase your astrophotography skills on the banner of next month's night sky blog, share your photos via our Royal Observatory Astrophotography Facebook group
You can also connect with us on Twitter @ROGAstronomers
Insight Astronomy Photographer of the Year
Come and see the fantastic entries and winner to the world's largest astrophotography competition in our free exhibition at the Royal Observatory until 22 July 2018.
See more of the night sky
Come on an amazing tour of this month's night sky in our Sky Tonight planetarium show delivered live by a Royal Observatory Greenwich astronomer.
Central image: © Shawna Cadwell
Resources for teachers and students
The Royal Observatory learning team have also created:
- Free animated videos that answer the biggest questions in astronomy and free resources to go alongside them.
- A whole host of podcasts featuring interviews with real space scientists, astronauts and active researchers working in UK Universities.