When you ask the average person what the brightest star in the night sky is, I bet the answer you get is the North Star.
Unfortunately that’s nowhere near the right answer. There are 50 other stars in the heavens that can brag that they’re brighter.
The brightest nighttime shiner is Sirius, also the brightest star in the constellation Canis Major, the Big Dog, that’s currently hanging in there in the low southwestern sky at evening twilight.
Don’t feel bad if you thought the North Star was the brightest. It’s probably because you’ve heard so much about it that you assumed that. The North Star is also known as Polaris, and that name befits its role in the night because it’s shining directly above Earth’s North Pole.
If you were looking down on Earth from Polaris you would have a rough time seeing our world below, since you would be perched 432 light-years or just over 2,500 trillion miles above our planet.
Since Polaris shines super high above the North Pole that makes it is an important star because all of the other stars, including the sun, appear to revolve around Polaris once every 24 hours.
It’s not the stars that are moving but rather us Earthlings rotating every 24 hours below the dome of the sky. If you were standing on top of the world at the North Pole, Polaris would be directly over your head with all of the other stars obediently revolving around the North Star. None of the stars would rise or set. We would see the same set of stars every single night.
But in the Northwest, the North Star is not overhead but rather fixed 24/7 halfway from the northern horizon to the overhead zenith. It’s easy to find with the help of the nearby Big Dipper.
This time of year the Big Dipper, which is actually the rearend and tail of the official constellation Ursa Major or the Big Bear, is hanging nearly upside down i high in the northeast sky.
The two stars that mark the side of the dipper’s pot section opposite the handle, Merak and Dubhe, act as pointer stars to Polaris. Just draw a line from Merak to Dubhe, continue that line beyond Dubhe and that will point to the lower left almost exactly at Polaris.
The North Star, by the way, is the brightest star in the much dimmer Little Dipper or Little Bear constellation Ursa Minor. No matter what time of the year, wherever the Big Dipper is in the northern sky, the stars Merak and Dubhe will always point at Polaris.
Constellations close to Polaris like Ursa Major and Minor, as well as Cassiopeia the Queen and Cepheus the King, make a tight daily circle around the North Star, and because they’re so close to Polaris they never set below the horizon.
They graze the northern horizon at their lowest point. These Polaris huggers are known as circumpolar stars. The rest of the stars in is the celestial dome that are farther away in the sky from Polaris also circle around the North Star once every 24 hours, but the northern portion of their circles lie below the northern horizon.
So to us they seem to rise at some point in the east and set at some point in the west during their cycle.
Not only do all of the stars circle around Polaris every single day and night, but they also shift to the west a little bit each night. That’s a good thing because that means we see different constellations from season to season through the course of the year as our Earth orbits the sun.
Upcoming celestial huggings
Friday and Saturday night the new crescent moon will be hanging by the bright Pleiades star cluster, otherwise known as the Seven Little Sisters. The Pleiades lie about 410 light-years from Earth.
Between 9 and 10 p.m. Friday the moon will be hanging below the Pleiades and on Saturday night the crescent moon will be a little fatter and higher. It will be hanging to the left of the Seven Little Sisters.
If it’s clear enough you may see a phenomenon called “earthshine” on the moon. Not only will you see the crescent moon being lit up by the sun, but you’ll see the rest of the moon’s disk bathed in a dull gray light. This light is secondhand sunlight bouncing off of Earth and onto the moon.
It’s a wonderful site. Shining just above the Pleiades and the moon will be the bright planet Jupiter, presently the brightest starlike object in the sky.
Mike Lynch is an astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and is author of “Stars, a Month by Month Tour of the Constellations.” Check his website, www.lynchandthestars.com. The Everett Astronomical Society: www.everettastro.org/.
Talk to us
> Give us your news tips.
> Send us a letter to the editor.
> More Herald contact information.
