As I write this, we have just finished a much-needed monsoon week. But today the clouds are gone, and the afternoon temperature is back into the 90s. It definitely feels like the dog days of summer are here. One reason these might be called the dog days is because Sirius, the dog star, is now roughly aligned with the sun. Because Sirius is the brightest star visible from Earth, an old story said that when it is out in the daytime, like at this time of year, its brightness contributed to the sun’s heat.
With Sirius out of the nighttime picture right now, that leaves yellow Arcturus and blue Vega vying for top honors as the brightest stars in our sky this month. Both are listed as magnitude 0.0, which makes them less than half the brightness of Sirius. Vega will be near your zenith. (i.e. the point straight over your head), and Arcturus is shining in the western sky. You can use the handle of the Big Dipper to help find Arcturus because the handle “arcs to Arcturus.”
Vega is in the constellation Lyra (the Lyre), a rather small constellation but one that has a couple of my favorite telescope targets. The visible stars in Lyra form a small equilateral triangle and an adjacent parallelogram. Vega is part of the triangle, and all the other stars are much dimmer.
Epsilon Lyrae is the dimmer star in the triangle that is away from the parallelogram. It is actually a multiple star system. With a small, low-power telescope, it is easy to see two equally bright stars. But with higher magnification, and at least a 3-inch diameter telescope, you can see that both stars in the double are also double stars. This double-double is a great test of the resolving power of a telescope, and I find it interesting that the four stars are so similar in apparent magnitude.
At the other end of the parallelogram from the triangle is the Ring Nebula, or M57, one of the more famous planetary nebulae. It is right on the line between the two stars, so easy to point your telescope to, but with low magnification, you might mistake it for just another star. Upon close inspection, you can tell it is a bit too fuzzy to be a star, and at higher magnification, you can make out the doughnut-shaped nebula.
A planetary nebula is an expanding cloud of gas from a mid-sized star nearing the end of its life. Our sun is expected to go through such a planetary nebula stage when it runs out of fuel in its core, rather than experiencing a big explosion.
The word planetary in the term planetary nebula is just descriptive – it means it looks small and disk-like in a telescope. The nebula part of the name just means they are fuzzy. So looking through a telescope, a planetary nebula is a small, disk-like fuzzy thing that has nothing to do with planets.
This monthComet Neowise C/2020 F3 is still visible but getting dimmer every night. Discovered in late March, it could be seen in the morning a month ago but has been in the evening sky since mid-July. It is to the left and a bit below the Big Dipper and a star chart or sky app will help you find it since it moves every night. Its tail is pointed upward now, which is about the same direction it is traveling. It was visible to the naked eye for a few days in July. Then it was blocked by clouds when it would have been getting higher and easier to see. Binoculars are needed now.
Jupiter and Saturn both made their closest approach to Earth last month, but this month are in an even more convenient position for evening viewing. They will be due south between 11 p.m. and midnight. This month Jupiter is almost 14 times brighter than Vega. And Venus, the morning star is almost four times as bright as Jupiter.
The Perseid meteor shower is typically one of the best ones of the year. It lasts for about a month and should peak on the night of Aug. 11 and Aug. 12. This should be a good year for meteor watching because the peak occurs over a week after the full moon.
Charles Hakes teaches in the physics and engineering department at Fort Lewis College and is the director of the Fort Lewis Observatory.