Graphic courtesy of Andy Veh
By Andy Veh, for the Redoubt Reporter
Daylight saving time ended Nov. 1. This will be a 25-hour Sunday right after Halloween. Clocks are reset to one hour earlier. If you forget to change your clocks, at worst you’ll be one hour early to meetings, appointments or family gatherings. Bring a book.
(A bill working its way through the Legislature at first sought to eliminate daylight saving time in Alaska, and with a recent amendment now seeks to change Alaska to multiple time zones. It’s currently in the Senate Finance Committee.)
For astronomy, the end of daylight saving time means the sky gets dark one hour earlier, from around 7 p.m. Oct 31 to 6 p.m. to Nov. 1.
Looking at the sky around 11 p.m., prominent constellations and stars are the Big Dipper (part of Ursa Major) high in the northeast and the Little Dipper high in the north. The three stars of the summer triangle — Cygnus with Deneb, Lyra with Vega and Aquila with Altair, are now low in the northwest. It’s perhaps comforting that in Alaska we can see this summer triangle all winter along, albeit near the horizon.
Cassiopeia appears overhead, in the zenith, and Pegasus’ square/diamond is in the southwest.
In the east, Gemini with Castor and Pollux, Cancer with the Beehive cluster and Leo have risen, following Orion with red Betelgeuse and blue Rigel, which are now high in the southeast (that’s why I chose the late evening for my description). Auriga with Capella and Taurus with Aldebaran, the Pleiades star cluster, currently with the very bright Jupiter, are now high in the south.
Neptune and Uranus are relatively high in the south in Aquarius and Pisces (both are below Pegasus). A good finder chart is needed, though. Try here. The first quarter moon joins Neptune on Nov. 19, and the almost-full moon joins Uranus on Nov. 21 and 22. That may make it easier to find them, but it also makes the sky brighter and diminishes the contrast.
Wait for the bright planets until morning. The spectacle that started last month continues — before dawn you can see very, very bright Venus, very bright Jupiter and fainter reddish Mars lined up, about to leave the constellation Leo and enter Virgo. They all rise in the East around 2 a.m.
Venus passed Jupiter on Oct. 25 and passes Mars on Nov. 2. The crescent moon joins Jupiter on Nov. 6 and Mars and Venus on Nov. 7. To their right (farther in the south) are 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 winter yet.
Just to the right of the three planets is Leo’s Regulus, which is about as bright as Mars. To the left, farther in the northeast, appears the red giant Arcturus. If you observe nightly you can see how they move (a combination of their own orbit and of Earth orbiting, as well) — Venus passes Mars and recedes from it since it orbits faster, and Mars recedes from Jupiter as it orbits faster. The diagram shows how the planets move in front of the background stars. On the left are stars in Virgo, on the right in Leo. So the star near Venus in mid-October is the blue giant Rho Leonis, which is 20 times more massive than our sun and four times as hot.
On its way to Jupiter, sunlight has to traverse eight times the distance compared to Venus, thus the amount of sunlight is reduced to 1/64. Jupiter is 12 times larger in diameter —144 times in surface area — thus reflects that much more of what is left of sunlight at its distance than Venus. That reflected sunlight traverses nine times the distance to Earth, compared to Venus again, so it’s reduced to another 1/81. The outcome is we get 30 to 40 times more reflected sunlight from Venus than from Jupiter. Therefore, the Morning Star appears much brighter than the Giant Planet. Continue reading