Astronomy

Claire Wardlaw, originally from Edinburgh, lives in the Charente with her husband. Since their move nearly 6 years ago, Claire has become passionate about astronomy.

By Claire Wardlaw

The Night Sky

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Now that we have, it seems, more and more of our normal freedoms returning to us, July is a month when the special astronomy event 'On the Moon Again' will be able to happen once more around the world and - regulations allowing - here in my own village in the Charente too. The nights will be lengthening a little again this month, which is always welcome for those of us who stargaze. One of the most easily found features of the summer skies - 'The Summer Triangle' - is stunning and very prominent throughout the summer months. Find out more details of where and how to see it below. Looking towards the north and south it is still possible to view much of our Milky Way as it stretches out through the constellations of Perseus, Cepheus, Cygnus, Aquila and Sagittarius. During a warm summer evening, catch four of our planetary neighbours - Venus, Mars, Jupiter and Saturn - as they orbit our star.

#On the Moon Again 21

In July 1969 man took his first step on the Moon. In 2019, to celebrate the 50th anniversary of this astounding part of our history, the first #onthemoonagain was launched and was enjoyed by hundreds of thousands of people attending more than 1300 events in 77 countries. This year #onthemoonagain is back. It will be an opportunity for stargazers young and old to look through a telescope and wonder at the stunning details of our natural satellite. On the 16th, 17th and 18th of July, many astronomers throughout the world, myself included, will be setting up telescopes and looking through binoculars to share the Moon with the public. If you have never looked at the Moon through a telescope, this is a great opportunity. It is a truly stunning sight. To search for events near you or, for a warmer, indoor experience of the 24 hour Lunar Marathon, go to the website www.onthemoonagain21.org.

The Moon and Planets this month

The month of July begins with a last quarter Moon. The New Moon will be on the 10th and as always the days either side of this will be the very best for making the most of the many other objects in our skies. The 16th, 17th and 18th will see the Moon entering its first quarter phase. These are the dates mentioned above when the #onthemoonagain events will offer some spectacular views of many Moon details. The Full Moon will be on the 24th. In the early morning of the 7th a thin crescent Moon will be seen close to Mercury low in the east north east just before sunrise. Mars (The Planet of War) is not very bright at the moment, but from the 11th to the 13th it may be easier to find as it will be very close to Venus as they rise from around 11pm. The bright and beautiful Venus shining away at magnitude -3.9 is also known as the Evening Star. Venus will be outshining Mars by 200 times. A thin crescent Moon and the star Regulus will also be close by. Jupiter, the gas giant, and Saturn will be seen rising in the south east from around 11pm. The Moon can be observed passing close by these planets from the 24th (when it will be full) to the 25th.

Meteor Showers

Meteor activity will be increasing in July as a few minor annual showers return to our night skies. The Capricornids will be active throughout the month, peaking towards the end of July. Although it only has an hourly rate of about 5 it can often produce very bright fireballs. They can be slow, yellow and blue meteors. The famous Perseid shower begins later in the month, around the 16th -23rd and lasts through to the last week of August. This is a very active shower with perhaps 90 meteors per hour. There can be many bright meteors with trails so I think I will be setting up my cameras to try and 'catch' a few throughout the night. (I will make a wish if I see any!) The Moon will be bright during these dates but it is still possible to .....' catch a falling star'!

Object of the Month: The Summer Triangle

This month brings the asterism known as 'The Summer Triangle' back to prominence in our night skies. It is called an asterism as it is made up of three stars from three different constellations. Firstly, Vega in the constellation of Lyra. It is the 5th brightest star and is 26 lightyears from Earth. Next we have Denab which is in Cygnus. This is the 19th brightest star and 1,500 light-years away. And thirdly there is Altair in the constellation of Aquila which is the 12th brightest star and 16.8 light-years from us. It is amazing to me that we see them as a linked pattern in our skies while in reality they are so very far apart. The Summer Triangle can be found after dark by locating Cygnus, or 'The Swan' as it travels almost overhead from the north east towards the south through a brightening Milky Way. The tail of the swan is marked by the star Denab and the head of the swan by Albireo. Once you have located the stars of the triangle it is possible to 'starhop' from there to many other constellations in our summer sky. It is one of the first things I look for when I head outside on a warm evening as it helps me to orientate myself. It is also like seeing an old friend again. As the summer triangle and the swan arrive in our skies it is a real marker of the seasons moving from spring to summer. As they continue on their journey towards the south this marks the move from summer to autumn.

Shining a Light on Astronomy Jargon: Retrograde Motion

If you observe the position of a planet over the course of a few nights it will seem to move further east compared to the position of the stars. At various times through the year the planets will seem to change direction and move in a westerly direction... before heading east again. This is known as 'Retrograde Motion'. This baffled ancient astronomers for many years. I have found it tricky to get my head round, I must admit. It was, however, brilliantly and simply explained to me while watching Episode 1 of the recent (lovely!) Brian Cox series 'Adventures in Space and Time' on BBC 2. I recommend a look at it. All he used to explain this planetary magic was a stick and some stones! As Brian said, this apparent change of direction is caused by our view of the planets from Earth as our speed of orbit changes our line of sight over the course of the year.

Constellation of the Month: Sagittarius

Sagittarius or 'The Archer' is to be found towards the south during this month and sits in a beautiful bright area of the Milky Way. When looking towards the boundary between this constellation and Scorpius you are gazing at a point which marks the very centre of our Milky Way. Within this area it may be that scientists will discover a supermassive black hole. Sagittarius (Sgr) is ranked 15th in size and covers 867 degrees of the sky. It was one of 48 to be named by the ancient astronomer Ptolemy around AD 150. Because the Milky Way is so rich with stars here it can be a little difficult to identify this large constellation, or to recognise an archer but you can spot more easily a 'Teapot'! The teapot asterism is easy to find and the star Nunki helps to form the teapot's handle. Nunki is one of the main stars of the archer's body. The star Gamma Sagittarii is the spout of the teapot. Sagittarius is rich with nebulae and star clusters. With binoculars and clear dark skies it may be possible to observe The Lagoon Nebula, also known as M8 and one of the largest nebulae in the sky. It will appear as an oval, grey shape with a brighter area to one side. The dark lagoon area of dust can be viewed using a larger telescope. 'The Sagitarius Star Cloud' or M24 is a rich starfield appearing three times the width of a full Moon. I have found this with binoculars in the past and it is a really beautiful part of the Milky Way .

This apparent change of direction is caused by our view of the planets from Earth as our speed of orbit changes our line of sight over the course of the year