What's Up in the Sky - June 2012

Fred Barrett | May 31, 2012

By Fred Barrett

Don’t you dare miss the Venus transit! It’s an event that won’t happen again for 115 years. It will occur between 6 p.m. and sunset on June 5. Please protect your eyes. Use #14 welder’s glasses or solar filters that can be bought at local optical shops or Focus Scientific in Ottawa. I will be by the side of regional road 36 about two kilometers south of Highway 7 at that time and will attempt to get some pictures through my 8-inch telescope. If you want to come by, please do but watch where you park! It is a narrow area.

This month I thought I would discuss how astronomers measure how far the stars are. There are five or so ways of how to make those sorts of estimates but with limited space I’m going to point out one method that gives us an idea of the acceleration of the expansion of our Universe, a recent discovery, and how the measurements were made. I won’t be too technical so don’t let your eyes glaze over yet! The Universe was once thought to be in equilibrium but, like life in general, sometimes it’s not that simple. The Universe will eventually, in numbers of years that are too large for us to really appreciate (several gazillion years), expand so far that the stars and the galaxies in the sky will be too distant to see! The sky will be completely BLACK and empty!

To measure the distance and the expansion rate of the Universe, astronomers use type IIA supernovas. The physics behind a stellar explosion like this and the brightness and energy it generates is completely predictable. Most star systems aren’t like our own Sun. There are usually two or more stars orbiting each other in what is called a binary or multiple stellar system. Over many, many years the stars orbit closer and closer until they eventually collide. The “luminosity” or amount of energy that they emit can be calculated very accurately. Allowing for transparency in the atmosphere and dust clouds that are between the supernova and our telescopes, their luminosity or energy emission can be well measured. Their brightness can be measured against a standard and an estimate of distance calculated. A few years ago, it was discovered that, according to the theories of that time about what the Universe was doing, their luminosity was less than it should have been! They were farther than was expected! Since then, newer theories have suggested that empty space is actually generating more empty space and causing the volume of our universe to expand! Who would have guessed?

This month most of the planets viewable are in the west after sunset. Saturn is an especially lovely sight through a moderate size telescope. Last night (May 26) the rings were well tipped to see divisions in their structure.

This month, the full Moon is on the 4th. There is again a partial lunar eclipse but only seeable way out west. The Moon is such a fascinating territory to view. I know that I keep mentioning it, but with a good set of binoculars, you can discover a whole new world! This month’s full Moon is called by various Aboriginal and European societies, the Rose Moon, Planting Moon, Green Corn Moon and Berry Ripening Moon. All names are pretty accurate even allowing for the weird spring that we have had.

Remember that summer solstice is on June 20 (7:09 p.m. EDT), and summer officially begins! For us amateur astronomers, that means that the days get shorter and the nights longer again. I hate to see winter approach but it really is the best time to observe! It’s so hard when the Sun goes down so late and it rises so soon. Summer has the most beautiful constellations but the shortest time to view them. To mention Saturn again, it’s prominent in the south in the early evening and right in the middle of Virgo. Do you remember how to find Virgo? The arc of the handle of the big dipper points down to Arcturus, a very bright blue star, and then just “speed on to Spica” and voila, you are in the bottom part of Virgo. At this time of the year, the band of the Milky Way, our galaxy of two billion plus stars, is especially prominent and is so beautiful when you look up high in the night sky, through a simple set of binoculars – what a universe! There are no meteor showers to report this month but there are certainly plenty of objects, a universe of objects, to tour in our dark skies. It’s cheap entertainment to walk outside where you live out in our rural areas and, with a little research, show your kids what’s going on or impress the neighbours with what you know!

On June 27 the moon is about a fist’s width below Spica and Saturn is quite close as well.

If you want a real challenge, get a telescope and look for Pluto in Sagittarius. I will leave it to you to find a star chart and search the sky to find that constellation. Get star searching!

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..