Jared May: What's Up, October 8 - October 15, 2021

What’s Up This Second Week of October

We are now in the heart of October, but the weather is not necessarily reflecting that. This week we can expect a handful of clear nights which become rarer as the seasons move through fall and into winter. The high temperatures are much warmer than the average for this time of year, even at night. The temperature will be in the mid-60s. Sunset this week is around 7 PM so be ready to stargaze by 8 PM. During this month Ohio, and other states around our latitude, will lose around an hour of sunlight. That is a little depressing but great for amateur astronomers and stargazers who just want to spend all their time outside at night.

This week be on the lookout for a young moon hanging with Venus, the first quarter moon, Jupiter’s Great Red Spot and Ganymede, the moon swinging by Jupiter and Saturn, and lots of fall star clusters. I also want to talk about a neat astrophysical phenomenon, the expansion of the universe, that can be used as the coolest pick-up line ever.

The “Celestial Trio of Jupiter, Saturn and the first quarter moon.

This weekend just after sunset, look low in the western skies for the young crescent moon. On Saturday the waxing crescent will be no more than 2° away from the evening star, Venus. A pair of binoculars or a telescope will reveal very contrasty craters and surface features on the moon. You may notice that as the sky darkens, the dark side of the moon will appear to have a faint glow. This phenomenon is called earthshine. It is caused by the earth reflecting sunlight to the moon and faintly illuminating its surface.

Tuesday, October 12th, will be the first quarter moon. If you think about what this implies about the positions of the earth, moon, and sun, you will realize it means they form a 90° angle. So, before sunset the bright side of the moon should point straight towards the sun. But the moon pulls off one of the biggest optical illusions – its bright side appears to point over the sun! This is caused by something called foreshortening.

Set up your telescope and point it toward Jupiter just after sunset on Monday, October 11th. If you use a longer focal-length telescope (around 1000mm) and a decent eyepiece, you will be able to watch an eclipse on Jupiter. Between 7 PM and 10 PM one of the Galilean moons, Ganymede, will be casting a shadow that moves across the cloud tops of Jupiter.

A shadow transit on Jupiter that will be seen right after sunset on October 10.

On Friday, October 8th, and Wednesday, October 13th, take a look at Jupiter using a green or blue color filter (these filters help give color contrast of Jupiter’s surface) and try spotting the famous Great Red Spot. It should be easy to find since it will be crossing the middle of the planet at 10:40 PM and 9:50 PM respectively.

Jupiter’s Great Red Spot crosses the center of the planet every 10 hours.

The waxing gibbous moon will be swinging by Jupiter and Saturn on Thursday, October 14th. While the moon will be bright enough to wash out some faint deep-sky object, this celestial trio will provide lots of amazement for anyone you go stargazing with.

The fall skies come with their own unique deep-sky objects and constellations, and one of the easier things to spot using binoculars or a telescope are the many star clusters rising in the east and northeast. Many of these clusters have fun names: m&m Double Cluster, Little Scorpion Cluster, Patrick Starfish Cluster, Lawnmower Cluster, and more.

Now for a little bit of astrophysics…

The universe is expanding, and this has been measured and quantified. Galaxies at different distances (or “z”, in cosmological terms) have different redshifts. A correlation was found that the further away a galaxy is, the more redshifted it is, meaning the faster it is moving away from us. This is much like the doppler effect, like when a train passes the horn has a slightly lower pitch when the train is moving away. There are two additional properties about the universe that are agreed upon: the universe is isotropic meaning the universe looks roughly the same in all directions, and the universe is homogeneous meaning the universe looks roughly the same at all points in the universe. For example, if we were to move to a completely different galaxy, all other galaxies would appear to be moving away from us. Because of these properties, it can be argued that any point is technically the center of the universe. So the next time you want to say something sweet to someone, tell them they are the center of the universe – quite literally!

Get outside this week and enjoy the handful of clear nights Ohio has gifted us. The warmer nighttime temperatures are an added bonus. Since it is getting darker earlier, there is no need to stay up super late to stargaze. This week be on the lookout for the young moon and Venus, the first quarter moon, a Jovian eclipse and the Great Red Dot, a celestial trio, and some fall star clusters all while technically being at the center of it all.