Jared May: What’s Up This Second Week of September
With the moon rising later in the night, earlier sunsets, and more reasonable temperatures, this upcoming week is a perfect opportunity for both people in a hurry and dedicated amateur astronomers to look up at the sky. Since sunset is right around 7:50 PM, the first stars and planets will start revealing themselves around 8:20 PM. After the sun disappears below the horizon the temperatures will drop very quickly. This week temperatures will go from mid/upper 70s to mid/low 60s, so make sure to bring a jacket if you plan on being outside for more than a few minutes. This week brings us the third quarter moon, Mars passing into retrograde, and the easy viewing of a nearby photogenic and binocular-friendly galactic neighbor.
Wednesday will be the third quarter moon, meaning the moon is exactly three quarters of the way through its month-long orbit (starting from “new moon.). The moon will rise around 11 PM on Monday, giving plenty of time before this to view a night sky unhindered by the moon’s blinding glow. It may be apparent to people who track the moon’s position regularly, but there is a pattern to the moon’s cycle if you don’t already know. Notice the resemblance between these two words, “moon” and “month”, well that is no coincidence. The moon takes 29.5 days, almost exactly one month, to make a full orbit around the Earth (each quarter phase is separated by just a bit more than seven days). So next week you can count on me reporting the new moon!
Wednesday will also display a stationary Mars as the red planet transitions into its retrograde motion. That’s right, over the next 70 days or so Mars will appear to move in the opposite direction to what it normally does. This is only an optical illusion and it’s fairly subtle to notice since the planets move relatively slow night to night. This retrograde illusion is caused by the relative motions of both Earth and Mars in comparison to fixed background stars. It is difficult to explain in words without a demonstration so I encourage you to watch this brief informative video explaining how Mars (and Mercury) appears to change its direction in the sky: https://www.youtube.com/watch?v=FtV0PV9MF88 .
Image published on the Astronomy Picture of the Day, a great website for daily astronomical images: https://apod.nasa.gov/apod/astropix.html
Over the coming months, our nearest large galactic neighbor, the Andromeda Galaxy ( (2.5 million light years away) will be in plain sight starting around 8:30 PM (for this week). Andromeda is one of the brightest deep-sky objects, in fact, it’s one of only a few that are naked eye visible (in darker locations). If you look or point your binoculars/telescope 40° above the east/northeast horizon you should hunt for a soft fuzzy glow that stands out from the background sky. This fuzzy glow is actually a collection of roughly 1 trillion stars circling a supermassive black hole at around 130 miles per second all on a collision course with our own galaxy. Do not worry about the collision part though, because that will happen in about 4.5 billion years and the odds of any stars colliding in the collision between the two galaxies is 1.1 x 10-19% (basically 0%). Andromeda is not only very easy to find with binoculars and telescopes, but it is perhaps one of the most photogenic deep-sky objects. Even a DSLR camera mounted to a tripod with a long exposure (30 seconds is sufficient sometimes) is able to resolve one of Andromeda’s own satellite galaxies, M32. That’s right, we can easily see a galactic companion of another galaxy!
https://apod.nasa.gov/apod/ap161227.htm
Image NASA’s APOD
The forecast ahead, however uncertain, is predicting a few clear nights this week. Go outside prepared with a jacket, a pair of binoculars or a telescope, and a lawn chair to prevent neck strain. The sky holds many spectacles that are both easily visible with the unaided eye and many that will only be revealed through the magnified view of a telescope. Enjoy the early sunsets and comfortable temperatures of summer’s end. Clear Skies!