What’s Up This Second Week of September

Stargazers and amateur astronomers will be blessed with a great gift this week – a forecast with several clear nights! The temperature will take a noticeable drop once the sun has set, shifting from the middle and upper 80s to the 60s over the course of just a few hours. Sunset will be around 7:50 PM so the fainter stars and deep-sky objects will be visible around 9 PM. It is interesting to think that just over two months ago sunset was at 9 PM and the night sky was fully dark at 10 PM.

This week be on the lookout for the thin crescent moon near Venus, the first-quarter moon passing Antares, Mercury high in the sky, and the Triangulum Galaxy. I will also include a short section about telescopes that work outside of the visible spectrum.

Thursday, September 9, just after the sun has set, look towards the western horizon and try spotting the young crescent moon hanging next to Venus. They will be separated by no more than 5°. Since they will both be near the horizon, the viewing window is only from 7:45 PM to 9 PM. Binoculars or a telescope will be great for both objects. The moon will be particularly interesting with high contrast along its terminus that will draw your attention to dramatic craters on the lunar surface.

The moon and Venus will make a lovely pair just after sunset on Thursday.

On Saturday, September 12, turn your attention to the south. You will see the nearly first-quarter moon situated just 3° away from a noticeably red star (although the moon’s brightness may wash the star’s color out). This red star is Antares, and it is part of the Rho Ophiuchi cloud complex. The moon’s light will prevent photos of this impressive deep-sky object, unfortunately.

On Saturday, the moon will be near the orange star Antares.

On Monday, September 13, the innermost planet, Mercury, will be at its greatest eastern elongation. In other words, it will appear to be at its furthest point from the sun. This makes it the ideal time to observe and photograph this tiny rock. Despite Mercury being at its furthest apparent distance from the sun, the window to see it is only from 7:50 PM to 8:15 PM with clear horizons. Even with a telescope, Mercury will appear to be no more than just a tiny white dot.

Mercury is usually difficult to spot. If you’ve never seen it, early next week will be a good time to try.

Most amateur astronomers and stargazers have heard of the Andromeda Galaxy, but many people do not know about another impressive nearby galaxy – the Triangulum Galaxy. Triangulum, Andromeda, and our own Milky Way are the three largest galaxies in the Local Group. In total, the Local Group is a small cluster of 30 galaxies with a center somewhere between the Milky Way and Andromeda. The Triangulum Galaxy shines at magnitude 5.7 which makes this an excellent binocular and telescope target under dark skies and can be found in the general area between Andromeda and Cassiopeia.

The Triangulum galaxy, M33, is the third largest galaxy in our “Local Group”. It is easy to spot in binoculars as a fuzzy blob. Here’s how to find it.

Alex Mullins took this image of M33 at JGAP.

All of the telescopes amateur astronomers and stargazers buy (even the astrophotography cameras) are designed for focusing and capturing light in the visible spectrum (or near-infrared), which is the same spectrum that our eyes can see. Very interesting astrophysics happens at different wavelengths (gamma, x-ray, infrared, microwave, and radio). For example, x-ray telescopes are used to observe the areas near black holes and stellar explosions whereas radio telescopes are used to study giant gas jets being spewed out from powerful galaxies. Unfortunately, many of these telescopes outside of the visible spectrum require very expensive materials for their sensors/cameras or unique lenses that make them inaccessible to the general public. Think of a typical telescope lens and you’re either picturing a piece of curved glass or a curved mirror. Well, my favorite type of telescope lens belongs to x-ray telescopes. They use tens or hundreds of nested metal circles that redirect x-rays to a focal point – weird! (https://imagine.gsfc.nasa.gov/observatories/technology/xray_telescopes1.html)

Enjoy the series of clear and cool nights this week – Ohio stargazers know this is rare to have so many forecasted clear nights. Bring your binoculars, telescopes, and a chair for stargazing as you look for the moon hanging near Venus, the first-quarter moon passing Antares, Mercury, and the Triangulum Galaxy. Contemplate the night sky as you see it with your eyes and telescopes in the visible spectrum, then imaging how colorful the sky would be in other wavelengths.

Clear Skies!

Jared May: What's Up September 9-16, 2021