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October Milky Way: Eye on the Night Sky

by John J. Beck

 

Even for those with little experience viewing the wonders of the night sky, October is a great time to view the Milky Way and other easily recognizable sights. Of course, one of the easiest ways to get started is to visit an event with amateur astronomers such as the Door Peninsula Astronomical Society’s scheduled viewing night on October 6. Watch the Peninsula Pulse for events sponsored by other astronomical groups in the area.

The full or nearly full moon makes the Milky Way difficult to see well with unaided vision, so checking a calendar for moon phases is helpful. On October 2 this year the last quarter moon doesn’t rise until about 4:45 am in our location, so there’s plenty of time for dark sky viewing. New Moon is on the 8th. The weekend of the 13th and 14th the moon sets between 9 and 10 pm, and on the 31st the last quarter moon doesn’t rise until around midnight.

Astronomical twilight determines sky darkness in relation to sunrise and sunset. On October 2 the sky is darkest from about 8 pm to around 5 am. That period is from about 8:30 pm to 5 am on the 31st. While you’re waiting for the sky to get dark enough to spot constellations you may see Saturn in the southwest and Mars in the south. 

This image shows the star-studded center of the Milky Way toward the constellation of Sagittarius. This image was taken with the Hubble telescope. Photo by NASA, ESA and G. Brammer.

Although the Milky Way is magnificent with unaided vision with clear skies and no light pollution, it’s even more striking with binoculars. You don’t need expensive binoculars to appreciate the myriad stars in the Milky Way. If you’re in the market for binoculars and wonder which is best for astronomy, that’s an entirely separate topic.

To find your way around, it helps to have a star map or planisphere. An October issue of Sky & Telescope or Astronomy magazine will have a sky chart, or you can download one from skymaps.com. Remember that with most sky maps you rotate it so that the direction you’re looking is at the bottom of the chart, then hold it over your head. You’ll notice that otherwise, west will be on the right of a north-south line instead of on the left.

Sagittarius the archer has move westward since summer. Look for the easily recognizable teapot asterism near the southwestern horizon. You’ll be looking toward the center of our Milky Way Galaxy, and the southwest end of the Milky Way. You’ll also spot Saturn near the teapot; binoculars or a small telescope will show that it’s a planet, not a star. You may even see the rings. With a telescope or binoculars you might view a globular cluster. Look for the symbols on your sky chart; there are several in the region. Each globular cluster is a tight bundle of hundreds of thousands of stars.

Following the Milky Way northeastward you’ll encounter the bright star Altair. You can try to make out the constellation Aquila the eagle of which Altair is its brightest star. Then moving on to nearly directly overhead, look for the Northern Cross, the asterism that marks Cygnus the swan who is flying southwestward along the Milky Way. The relatively bright star at the tail of Cygnus (or top of the cross) is Deneb. The head of the swan or bottom of the Northern Cross is Albireo, nearly midway between Altair and the brightest star just north of the Milky Way, Vega. Even binoculars may show Alberio to be a double star with interesting color contrast between the two component stars. Vega marks the constellation Lyra the lyre, and telescope users have fun focusing on the Ring Nebula in that constellation. Lyra lies just northwest of the Milky Way. Between Aquila and Cygnus you may have noticed Sagitta the arrow and Vulpecula the little fox, and telescope viewers may find the Omega or Dumbbell nebula in that vicinity.

Continuing northeast along the Milky Way is that most recognizable asterism, the W which marks the constellation Cassiopeia the queen. If you continue northeast at right angles to the most northern pair of stars in the W, with binoculars you can enjoy the Double Cluster in Perseus. Continuing toward the horizon you’ll see a string of stars in Perseus. Very close to the horizon you may see the bright star Capella and part of the constellation Auriga the charioteer, which completes our tour of the October Milky Way. 

Some constellations look like people or animals. Sagittarius looks like a teapot. Image courtesy of NASA.

When we look at any stars in any direction, they all are within our Milky Way Galaxy. An exception is that when we view the Andromeda Galaxy with binoculars we’re looking at an entirely separate galaxy but we can’t begin to resolve individual stars. Picture yourself standing on Earth in our galaxy looking different directions. You can’t see all around the galaxy because Earth blocks your view of about half of it, and what you can see appears to be tilted in relation to how you are standing. But when you look toward the edge that you can see, what you see is the Milky Way. When you were looking at Sagittarius at the beginning of the tour, you were looking toward the center of our galaxy.

Now you can count yourself as someone special because you were in Door County where, on a clear night with no surrounding light pollution, you’ve appreciated the Milky Way. Eighty percent of the people in the United States are unable to see the Milky Way because of light pollution.

More astronomy information for all ages will be presented at the fall

Astronomy Day activities on October 20. Watch for details to be published in the Peninsula Pulse and elsewhere.

Questions or comments about this article may be addressed to [email protected]

 

“Eye On the Night Sky” is a monthly column by the Door Peninsula Astronomical Society. For more information on the organization, visit DoorAstronomy.org.

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