What’s up in the sky – July 2010

Fred Barrett | Jun 30, 2010

By Fred Barrett

This month and next provide a feast of stellar targets for binoculars and wide field telescopes. There are enough nebulae, galaxies, globular and open clusters to satisfy the greediest of stargazers and most are quite easy to find! There’s a catch though. Isn’t there always? In mid-summer, dark enough stargazing skies arrive late in the evening and the sun starts poking its light above the eastern horizon and spoiling the fun much too early! A defense against hungry, buzzing flying critters must be found as well. Be careful using anti bug spray or fluid. Some brands can damage equipment, literally melt plastic. To be safe, I use burn coils. The viewing rewards at mid-summer more than make up for the extra challenges.

We are visiting Sagittarius this month. It is often called “the teapot’ because the most prominent stars appear to outline the shape of a teapot. It is also called “the milk dipper” for the same reason. The ancient Greeks and Romans who named the constellation thought it looked like a centaur shooting a bow and arrow into the heart of Scorpius, the scorpion. Note that “Sagitta” is Latin for arrow. It sits at the very heart of the Milky Way and there are many deep sky objects to see and study. It is also where you can find the centre of the Milky Way Galaxy. A few degrees off the star at the spout of the teapot, Gamma Sgr (Sagittarius), and approximately 27,000 light years away through countless dust clouds, lies the galactic centre of rotation.

The attached sky chart shows the constellation Sagittarius, the Archer. The easiest way to find Sagittarius is to face south, look up at the Milky Way as it arches overhead and follow it down towards the horizon. In early July Sagittarius is a little east of south and about 15 degrees above the horizon. Remember that a closed fist at arm’s length is 10 degrees. Using the chart find a prominent star or two and you should be able to trace out the outline of the teapot quite readily.

There are 15 Messier objects in Sagittarius and no other constellation has so many. Below is a list of some of the brightest and most impressive Deep Space Objects (DSO’s) to observe. Use the chart with this column or one from your own observing guide to find them. You can challenge yourself with the others.

M 8, the "Lagoon Nebula", is thought to be about 4000 light years away. A dark band splits this diffuse nebula in two. It is easily a naked eye object but much more detail can be brought out with a medium sized scope. In the eastern part of the nebula you can find the open cluster NGC 6530. This young cluster is only a few million years old and is nicely contrasted against the nebula.

M 17, the "Swan Nebula" or the "Omega Nebula", and sometimes called the "Horseshoe Nebula" looks like the tail of a comet. It appears like a bright diffuse trail of light with a bit of a hook on it. It is about 5000 light years away. Just below it and a bit to the right is M18. It is an open cluster of about twenty stars.

M 20, the "Trifid Nebula", is another delight. You will need a scope to bring out three dark dust lanes. Trifid means “divided into three lobes” and the dark lanes divide the nebula into the trifid shape. In the same field is M21, an open cluster of about fifty stars to the left and a half degree above or North of M20. The Trifid Nebula is found 1-1/2 degrees above the Lagoon Nebula.

M 22: It’s a marvelous globular cluster situated 2 degrees North East of the top star of the Teapot: Lambda Sgr (Sagittarius). M22 is a highly concentrated group of five hundred thousand stars about 20,000 light years away. While you are in this area, have a look at M28. It’s a bit hard to find 1 degree North of Lambda Sgr.

M 23: An open cluster of about 120 stars scattered loosely about 5 degrees North of M20.

M 24: It’s a bright "star cloud", a bright part of the Milky Way. It is quite prominent and beautiful and easily seen naked eye. Look for the open cluster NGC 6603 contained within its brightness.

M 54: is a globular cluster and it’s difficult to see. I mention M54 because it is thought that it may be the nucleus of the Sagittarius Dwarf Elliptical Galaxy (SDEG) which has been gravitationally captured and disrupted by our Milky Way. It takes professional level equipment to see this galaxy.

As July begins, look west about 45 minutes after sunset. You can see the star Regulus in Leo sitting between Mars and bright Venus. The three form a downward slanting line. Saturn is situated roughly 15 degrees along that line above Mars. As the month progresses watch these planets get closer and closer until by the end of the month they form a tight narrow triangle. Mars will be very close to Saturn, within 2 degrees. At mid month Mercury makes an appearance to the lower right of Regulus and by month’s end sits above Regulus and about 20 degrees from Venus. All four planets are in view! A good clear Southern horizon is a must.

Saturn makes its appearance about midnight in early July and I can attest that it’s very bright. It rises by about 10:30 by month’s end. Saturn and its moons are a fantastic binocular view!

The Earth is at aphelion, its farthest point from the Sun, at 7 AM EDT on July 6. That distance is 94,508,000 miles or 1.67% farther than its average distance. Yes, the Earth is actually farther from the Sun in mid- summer than in mid- winter!

Watch the waxing crescent moon pass by the line of planets on the 14th and 15th. Full Moon this month is on the 25th and is called the “Thunder Moon”. Thunderstorms happen more frequently in July. It’s also named the “Full Buck Moon”. Normally this is the month when the new antlers of buck deer sprout from their foreheads. New Moon is the 11th.

Were you able to see Comet McNaught last month? It was a beautiful sight. I was able to view it on several clear 3AM mornings from early June to late June. I was unable to get a decent picture unfortunately.

Editor’s Note: Tomorrow, July 1, Fred will be the guide for the stargazing portion of a Canada Day Ceilidh and Stargazing event at the Davidson Glengyle Farm, 2208 Hwy. 511, between Lanark and Balderson. The event is a fundraiser for the Mississippi Madawaska Land Trust Conservancy (MMLTC) and tickets are $15, $25/couple. Also, at “Pie in the Sky”, which will be held at the Maberly Fairgrounds on Saturday July 3 from 8:30AM to 1PM, Fred will be offering free views of the sun through a special telescope.

If you have questions or suggestions, Fred Barrett may be contacted at This email address is being protected from spambots. You need JavaScript enabled to view it.

The Beginner’s Observer’s Guide by Leo Enright is available at the Sharbot Lake Pharmacy or by contacting the Royal Astronomical Society of Canada www.rasc.ca/publications, subscriptions for our very own excellent Canadian astronomy magazine, Sky News, are also available from RASC..