Algol is one of the stars in the constellation Persius that sits below Cassiopeia. Its Arabic name means head of the ghoul, or head of the demon. Beta Persei is the official name, but Algol is more common because of what it means.
The mystery of this star came from the fact that it varies in brightness over a regular time interval of 2 days, 20 hours and 49 minutes. Ancient stargazers didn’t know why this happened, and thought Algol was associated with demons, hence the name.
But now it’s quite simple to understand. Algol is a multiple star system where one star passes in front of the other as they spin around each other. There are three stars, but only two visible to us that cause this light change.
The larger star is the fainter one. So, when it passes in front, from our view, Algol becomes dimmer. Then when the smaller but hotter bright orange star moves to the front, Algol changes color and becomes brighter. Both stars are visible with the naked eye, but the dimmer one will shine on Oct. 30. Then, on Nov. 2 you’ll see Algol at its brightest.
To find Algol, first find Cassiopeia in the northeast and look below for Perseus. It’s a rather large constellation in the shape of a man. You’ll have to be creative to envision it. It has a triangular-shaped body with its brightest star Mirfak on the lower left body where the leg begins. Algol is to the right of Mirfak anchoring the other side of the body. Perseus will be visible all winter. If you look at it every night for a few days, you’ll see the difference in Algol’s color and brightness.
Daylight savings time ends Nov. 2. So, you’ve got one more week, and then it changes. The good thing about that is that it will be dark an hour earlier, so you’ll be able to look at the sky in the evening. The unfortunate part is that it gets light an hour earlier in the morning, so you’ll have to get up earlier for morning viewing.
The zodiacal light will be visible until Nov. 4, about 1 ½ to 2 hours before sunrise. Currently that is 5:30-6 a.m. Mercury is also visible at that time sitting low in the east where the sun rises. The Orionid meteor shower peaks on the 21, so it’s time to go out and observe them. Oct. 20 to 22 there will be 20 to 25 meteors. Remember they’re in the NE, but they will go through the sky.