Thanks to the help of SLU Professor Aileen A. O-Donoghue and Dominic Ford’s incredibly informative astronomical calendar, I may bring to you this week’s sky events:
This week’s sky show is looking to be a rather quiet one, but we will still have plenty to discuss with these few events—including one in particular that I am rather excited about. Peaking on Wednesday, Nov. 17, the 2021 Leonid meteor shower will last until the end of this month. This shower’s radiant point—meaning the place in the sky in which it can be found—will be in the constellation Leo. As you may know, Leo is one of the 12 constellations associated with the zodiac signs. These constellations lie within the suns path, known as the ecliptic, and our sign is determined by which constellation the sun is lying in when we are born. However, did you know that there is actually a thirteenth constellation along the ecliptic that gets left out of the zodiac? The constellation is called Ophiuchus, but it is not included because 3,000 years ago the Babylonians, who created the zodiac, decided 12 was better than 13 for some reason. I think this is an interesting bit of information to note because it means that for anyone born between Nov. 29 and Dec. 17, the sun was not in Scorpio or Sagittarius, but in Ophiuchus. What does this mean for these individuals? Do they just technically not have a zodiac sign? I guess it depends on whether one puts more value on the chart itself or on the actual placement of the stars.
Anyhow, this Leonid shower will likely not be visible until after midnight, when Leo makes its way above our northern horizon. Also, on the night of Nov.17, M45, or the Pleiades open star cluster, will be visible in Taurus—which is another one of our familiar zodiac constellations. It will first be visible at around 6:00 p.m. as it makes its way above our horizon, but it will be most visible later on, since it will be placed higher in the sky. The magnitude of Pleiades is a 1.3, making it visible to the naked eye—since smaller numbers of stars’ magnitudes actually indicates that they are brighter. So, a star that is a magnitude of five would actually be dimmer and you would need binoculars to see it.
Skipping to Nov. 19, we will be seeing something a little exciting. First, there is the full moon, indicating a half way mark through our current Lunar cycle. Second, there is the partial lunar eclipse. Sounds exciting right? Basically, with a partial eclipse, it means that, for a moment, the full moon will pass through the earth’s shadow. Ford estimates that the maximum eclipse will occur at around 4:04 a.m. EST, when 97 percent of the moon will lie in the Earth’s shadow. It is worth noting that the show does not actually start at 4:04. It would be a good idea to start observing much earlier so you can watch as the earth’s shadow creeps across the moon’s fully lit surface.
One might be wondering why eclipses occur only sometimes. You would think that eclipses would either never happen or happen every month, but they don’t. This is because the moon’s orbit must perfectly line up with the earth’s in order for the shadow to be present. Usually, they move on totally different planes. Therefore, the moon is sometimes slightly below or above and only on rare occasions does it line up perfectly. Think of it this way, if you tied a marble to a hula hoop with a string and swung the hoop around, the little ball would not stay perpendicular to the hoop. Instead, it would sway up and down as it swung around, only on occasion being placed perpendicular to the hoop. One would get a different result if, instead of a string, the marble was attached to something rigid, like a stick. So, in the case of the moon, imagine its orbital plane as a tether to earth, like a kite, rather than as a fixed rotation. I hope that was helpful. I know this was something that puzzled me for a long time! As always, be sure to look up at your sky, it will always be there and it will stay relatively unchanged, but that doesn’t mean it can’t be dazzling.