What’s Up: October 2021

What's Up for October? What to look for this month at sunrise and sunset, and two brilliant stars vying for the "pole" position.

On October 10th look for the five-day-old crescent Moon to join Venus and bright, orange-colored Antares in the southwest after sunset. Then watch as Venus closes on Antares, for a close conjunction on the 15th and 16th, where the two will be only about a degree and a half apart.

During the last week of October, Mercury pops briefly into view for early risers.

Look for it about 10 degrees above the eastern horizon, or about the width of your fist held at arm's length, about 30-45 minutes before sunrise.

Then on October 30th, in the last couple of hours before daybreak, look for the 24-day-old crescent Moon to join brilliant blue-white star Regulus.

All month long, look high overhead early in the evening to find two bright stars that take turns with Polaris being the North Star. Their names are Vega and Deneb. Both of these stars are part of the Summer Triangle, and we introduced the other member of the trio, Altair, in last month's video. To find Vega and Deneb, look high overhead in the first few hours after it gets dark. They'll be two of the brightest stars you can see up there.

Vega is a bluish-white star, and like Altair, it's a fast rotator, spinning every 12 and a half hours, compared to the Sun's 27-day rotation. NASA's Spitzer Space Telescope found Vega to have a debris disk around it that could be similar to regions in our own solar system.

Deneb is a blue-white supergiant star that is fusing hydrogen at a phenomenal rate.

With this sort of fury, the party won't last all that much longer. Deneb is likely headed for an explosive end as a supernova within a few million years. Deneb is much farther away than most bright stars in our night sky. This means it's SUPER luminous to be that bright from so far away. Because it's so bright, it's one of the most distant stars you can see with the unaided eye.

These stars rotate around the northern celestial pole, and this time of year, they dip toward the western horizon before setting in the pre-dawn hours. Both Vega and Deneb are part of a special group of stars that take turns being the pole star in the north, as Earth's axis wobbles in a circle over a period of 26,000 years. For now the distinction of "North Star" belongs to Polaris, for at least a few hundred years more.

Finally, October 16th is International Observe the Moon Night, when everyone is invited to learn about the science and exploration of the Moon. Visit this link to find out how you can take part.

You can catch up on all of NASA's missions to explore the solar system and beyond at nasa.gov. I'm Preston Dyches from NASA's Jet Propulsion Laboratory, and that's What's Up for this month.