A look at long-ago Andromeda Galaxy
Fall has definitely arrived with cooler temperatures and the mandarins on my tree beginning to turn orange. In the evening sky, the Pleiades are rising in the east at sunset followed by the rest of Taurus soon thereafter.
As the season between summer and winter, the autumn sky sees the Summer Triangle stars — Deneb, Vega and Altair — setting low in the west in the evening as the winter constellations Orion, Gemini and Canis Major rise in the east.
By 6:30 p.m., the Great Square making up the body of Pegasus is almost due south. Coming off the top left corner star of the Great Square are two strings of stars that make up the constellation Andromeda. Just above the second star in the top string of Andromeda is a little fuzzy patch that is the farthest thing you can see in a dark sky, the Andromeda Galaxy (also known as M31, the 31st object in Charles Messier’s catalog of fuzzy things that are not comets).
The Andromeda Galaxy is about 2.5 million light-years away, so the light we see coming from Andromeda now left the galaxy about 2.5 million years ago (we see the galaxy as it was about 2.5 million years ago). Looking into the past is what astronomy does. The fuzzy patch we see without a telescope is just the central bulge part of the galaxy. Being slightly bigger than our home galaxy, the Milky Way, Andromeda has about a trillion stars (give or take a few billion stars) with spiral arms that would extend out several times the size of the moon on our sky if we could see them without a telescope.
Just about all galaxies have most of their mass made of material that does not interact with light (it doesn’t produce any form of light nor does it block any form of light). We call it “dark matter” for lack of anything better to call it and because we’re still a bit in the dark about what the heck it is. The Milky Way has proportionally more dark matter than does Andromeda, so even though Andromeda has more stars, the total mass of each galaxy is about the same. This month, the giant planets Jupiter and Saturn are high in the south shortly after sunset on either side of Capricornus. Although the planets do move with respect to the stars, they move slowly, especially the outer planets, so you’ll see them rise and set with a given constellation throughout a night.
As an inner planet close to Earth, the bright planet Venus moves a bit more quickly. This summer and fall, Venus has been the bright “evening star” in the west. Tonight, a thin waxing crescent moon is going to be just to the right of Venus.
The moon will be at first-quarter phase, looking half-lit from our vantage point on Earth, on the night of Nov. 10/11 (the “first-quarter phase” means the moon is one-quarter of the way through the phase cycle as it orbits Earth). The moon will be at full phase on the night of Nov. 18/19 and, according to the bookmark with the full moon names from the Old Farmer’s Almanac a friend from church gave me, this full moon is known as the Beaver Moon because this was the time of year the beaver traps were set before the rivers froze.
This full moon is also going to go almost completely through the umbra (darkest part) of the Earth’s shadow to make an almost total lunar eclipse. The moon will begin entering the umbra at 11:18 p.m. on Nov. 18, the midpoint of the eclipse will be at 1:03 a.m. on Nov. 19, and leave the umbra at 2:47 a.m. Ninety-seven percent of the moon will be in the umbra at the midpoint, so the moon will take on the characteristic orange-red color of a total lunar eclipse. How dark red the moon appears will depend on the amount of dust and ash in the atmosphere worldwide: A clearer atmosphere worldwide makes an eclipsed moon yellow-orange while a worldwide atmosphere with a lot of dust or ash from a large volcanic eruption can make the moon turn a dark ruddy brown.
The previous night of Nov. 17/18 will be the peak of the
Leonid meteor shower, which will produce 10 to 15 meteors per hour. However, the nearly full moon is going to wash out all but the brightest meteors.
Tickets for the “Season of Light” holiday show at the planetarium go on sale on Nov. 18. Proof of vaccination and mask-wearing are required for all indoor Kern Community College District events.