From EarthSky : “Double stars: How to find observe and enjoy”

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From EarthSky

November 17, 2021
Kelly Kizer Whitt

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The Big Dipper has 2 parts: a bowl and a handle. Look closely at the handle stars hanging down from the Big Dipper in this photo. Can you spot the double star? Image: Nadiia Ploshchenko via Unsplash.

Double stars are two stars that appear close together in the sky. They might be physically related or they might only appear to lie together along our line of sight. Double stars that aren’t gravitationally bound systems – but are only located near one another along our line of sight – are optical doubles. Double stars that are gravitationally bound and orbit a common center of mass are true binary star systems. Unlike our sun, scientists believe that most stars in our Milky Way galaxy orbit the galactic center in binary pairs. In fact, some estimates suggest that up to 85% of stars might reside in binary systems.

Like snowflakes, no two double-star systems are alike. So gazing at them is a lot of fun. You’ll see a huge range of star brightnesses, and a range of different distances between the stars. And sometimes you’ll notice a contrast in colors between the two stars. This post will give you some tips on observing double stars with your eye alone, with binoculars and, if you want to take the plunge, with a small telescope. Read on, and learn to enjoy the sky’s delightful double stars!

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This chart of the Big Dipper includes a label for Mizar, while its companion star, Alcor, appears next to it without a label.

Once you get used to spotting double stars, you’ll find them in constellations everywhere. Good luck, and clear skies!

See the full article here .


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Deborah Byrd created the EarthSky radio series in 1991 and founded EarthSky.orgin 1994. Today, she serves as Editor-in-Chief of this website. She has won a galaxy of awards from the broadcasting and science communities, including having an asteroid named 3505 Byrd in her honor. A science communicator and educator since 1976, Byrd believes in science as a force for good in the world and a vital tool for the 21st century. “Being an EarthSky editor is like hosting a big global party for cool nature-lovers,” she says.