The week ahead is forecasted to have a few clear nights, including Monday and Tuesday night. The midday temperatures are still following the warm summer trend, but the nighttime temperatures are revealing of the season to come. A jacket is almost necessary in order to observe the night sky comfortably with air temperatures dropping into the 50’s. Of course, there’s all that smoke from the unprecedented western wildfires, making even “clear” skies difficult to see through. So be sure to look up before setting out. If the smoke blows away from us, it should be uncommonly clear.

This week brings us the new moon (as promised from last week’s blog), a chance to see the zodiacal lights (if the smoke goes away), and a great chance to be a part of a citizen science group for variable stars!

The moon will rise in the very early morning hours this week just before the sun does. The official new moon occurs Thursday at 7:00 AM EDT. The clear night skies will be even darker this week without the moon’s white glow. On Tuesday morning the moon will be relatively close to Earth’s twin, Venus. They will be separated by roughly 12° in the eastern skies.

Venus and the moon in the Morning skies on Tuesday morning.

Venus, the brightest “star” in the sky, will be passing by the bright and beautiful open star cluster M44 (also known as “The Beehive Cluster”). Scanning the sky just a few degrees above Venus with binoculars will reveal the brilliant collection of young stars.

Messier 44, the “Beehive” cluster in Cancer. Visible in the morning skies at this time of year, when the air is clear, it appears as a faint fuzzy patch to the naked eye.

Since the moon’s light will be absent for most of the nights this week it is a perfect opportunity to observe something called the zodiacal light. This light appears as a soft triangular glow the extends from the Sun and runs through the ecliptic (the plane that the planets lie in) caused by dust scattering sunlight. The dust here is not the normal kind that floats around in your house or that settles on old books, it is actually dust that floats around in the solar system. Some of the early material that eventually coalesced to form the inner planets, including the Earth, is still floating around out there. It is normally very difficult to see the zodiacal light because of light pollution or the overpowering glow of the moon, so this week is perfect with an approaching new moon and clear nights in the forecast.

Any time of the year can be a good time to observe variable stars, although, it may be difficult to pick them out since many variable stars fluctuate in brightness over the course of many days or months. “Variable star” is an umbrella term than encapsulates many different types of stars that vary in brightness. There are Cepheid variables, eclipsing binaries, RR Lyrae variables, and more, each with their own unique properties, periods, and implications. The American Association of Variable Star Observers (AAVSO) is an organization that not only has the world’s most comprehensive variable star database, but gathers data largely from volunteer citizens!

https://www.aavso.org

What’s great about this effort is that you do not need to be a professional caliber amateur astronomer to take part. In fact, you can make observations and take data with as little as a pair of binoculars or even just you unaided eyes.

The brightness fluctuations of a variable star. Magnitude (brightness) is measured in by a curious system where lower numbers mean a brighter object.

Professional astronomers do not have the time nor the equipment to take such massive surveys of night-to-night changes of so many variable stars. When you sign up to get involved you can specify what equipment you have and since it is completely voluntary, you can observe anywhere from several times a week to only few times a year. There are lots of resources through this organization some of which include classes on observing and software, mentors, and tutorials. I am personally involved in data collection on a variable star in the constellation of Cassiopeia.

With the number of warm nights left questionable, take advantage of the surprisingly decent weather outlook for this week and enjoy the dark clear skies of summer’s end. Nighttime observing is becoming more “accessible” now with sunset approaching 7:30 PM. Bring a telescope, binoculars, or even just your eyes to dive deep into the wonders of the cosmos.

Clear (smoke free) Skies!

Jared May: What’s Up the Third Week of September