By Andy Veh, for the Redoubt Reporter
Compared to September, the constellations in the October night sky have shifted toward the east. Bootes sets in the northeast, with its brightest star, Arcturus, seen in the early evening on the northeastern horizon.
Prominent constellations and stars this month are the Big Dipper (part of Ursa Major) low in the north, and the Little Dipper (part of Ursa Minor) high in the north. Cygnus with Deneb, Lyra with Vega and Aquila with Altair are still high in the west. These three stars form the summer triangle. It’s perhaps comforting that in Alaska we can see this summer triangle all winter along, even if only on the horizon.
Cassiopeia appears overhead, near the zenith, and Pegasus’ square/diamond is high in the south. Very late in the evening, Orion rises with Betelgeuse and Rigel in the east, following Taurus with Aldebaran and the Pleiades star cluster.
It still seems that the planets are hiding from our view. At least in the evening, no bright planets appear. Still, try to observe Neptune and Uranus, which appear relatively high in the south, in Aquarius and Pisces (both are below Pegasus). A good finder chart is needed, though. Try http://www.skyandtelescope.com/wp-content/uploads/WEB_UrNep_Finders.pdf.
The almost-full moon joins Neptune on Oct 22, and the full moon joins Uranus on Oct, 25. The moon may make it easier to locate them, but it also makes the sky brighter and diminishes the contrast.
While Saturn is a fair distance from our sun, it is also in the constellation of Scorpius, which is very low on the horizon in Alaska, so it can’t be observed this month.
Wait for the bright planets until early morning for a good spectacle. Before dawn you can see very bright Venus, bright Jupiter and fainter, reddish Mars clustered in the constellation Leo. Mars would be one of the brightest objects in the sky but dazzling Venus and Jupiter outshine it. To their right (farther to the south) are the bright stars Procyon and Sirius and the winter constellations Orion and Taurus. They are not yet prominent in the evening sky because it’s not yet winter. Just to the right of the three planets is Leo’s Regulus, which is about as bright as Mars. To their left, but very low on the eastern horizon, is Mercury, best viewed in the middle of the month.
What adds to the spectacle is that it is easy to see how the planets move. Early in the month, the three planets are still spread out with Mars close to Regulus and Venus to the star’s right. Then they move in on each other, with Venus passing Regulus on Oct. 9, when all of them are joined by a waning crescent moon. Mars and Jupiter will be extremely close Oct. 17, with Venus starting to take on Jupiter and Mars on Oct. 24. The word planet means “wanderer,” and it will be beautiful to see this planetary dance that shows how planets move through the solar system.
The diagram shows two views of Leo with its brightest stars and the three guest planets labeled, about two weeks apart, each around 5 a.m.
You don’t need binoculars or a telescope to view these planets, but they help and would make it possible to see Jupiter’s four largest moons and Venus’ current quarter phase.
While conjunctions (clustering) between planets are remarkable, they are actually not that rare. In just the past century, Mars, Jupiter and Venus had six close encounters. That high frequency is simple to explain, since all planets orbit in the same plane around the sun. So, as seen from Earth, they all move along the same path (each near the ecliptic). Since their orbits are very periodic, they often encounter each other, as seen from Earth.
As a final thought, I was just about to look up when the planets are retrograding (as Mercury, Uranus and Neptune currently are) to present some more information about how these presently clustered planets move, but unfortunately, all the highest hits in my Google search were written by my nemesis — astrologers. At least they’ve got the information I was looking for.
Years ago I wrote in an astronomy column that, “I wish I had the time to write an astronomy column every day. But while holding down a serious and respectable full-time job, it’s hard to compete with astrologers, getting paid to make up stuff. I assume that, from a reader’s perspective, horoscopes are nice entertainment, just as I read the cartoons and Dear Abby on the same page and do the Soduko. I wonder how it looks from the astrologers’ side? Maybe it’s a hard job after all, since inventing short stories does require quite a bit of creativity.”
Andy Veh is an associate professor of physics, math and astronomy at Kenai Peninsula College.