Check the quality of your sky with Orion! | Night sky
Have you ever wondered how many stars you can see at night? From a perfect location with dark skies, free from any light pollution, a person with excellent eyesight can see a few thousand stars in the sky at a time! Unfortunately, most people don’t like flawless dark skies – and knowing the brightness of your sky will help you navigate the night sky.
The brightness of planets and stars is measured in terms of apparent brightness, or how bright they appear from Earth. Most visible stars have a magnitude 1 through 6 in magnitude, with the lower number being brighter. A star of strength one appears 100 times brighter than a star of strength six. Some stars and planets shine even brighter than the first magnitude, like the brilliant Sirius with a magnitude of -1.46 or Venus, which can shine brighter than -4! Very bright planets and stars can still be seen from bright cities with a lot of light pollution. In perfect skies, an observer can see stars as bright as 6.5, but such fantastic conditions are very rare; In much of the world, man-made light pollution drastically reduces people’s visibility at night.
Your heaven is Limit size is simply the measure of the darkest stars you can see if you look straight up. So if the darkest star that you can see from your back yard is size five, then your limit size is five. Just right? But why do you want to know your limit size? It can help you plan your observation! For example, if you have a bright sky and your limit brightness is three, watching a meteor shower or looking for darker stars and objects can be a wasted effort. But if your skies are dark and the limit is five, you should be able to see meteors and the Milky Way. Knowing this number can help you measure the light pollution in your area and see if it gets better or worse over time. And regardless of the location, be it a backyard, balcony or park with dark skies, light pollution is a problem for all stargazers!
How do you find out the limit size in your area? While you can use smartphone apps or dedicated devices like a Sky Quality Meter, you can also use your own eyes and maps with bright constellations! The Night Sky Network offers a free printable Dark Sky Wheel with the stars of Orion on one side and Scorpius on the other, here: bit.ly/darkskywheel. Each wheel contains six “wedges” that show the stars of the constellation, which are limited to one to six sizes. Find the wedge with the faintest stars you can see from your area; You now know your limit size! For maximum accuracy, use the wheel when the constellation is high in the sky well after sunset. Compare the difference between a full moon and a new moon. Before you begin, allow your eyes to get used to for twenty minutes to ensure that your night vision is optimal. A red light can help maintain your night vision while comparing stars on print.
Did you have fun? Contribute to science with monthly observation programs from the Globe at Night website (globeatnight.org) and catch up on the latest NASA science about the stars, which you can – and cannot see – at nasa.gov.
This article is distributed by the NASA Night Sky Network. The Night Sky Network program supports astronomy clubs in the United States that are dedicated to astronomy work. Visit nightsky.jpl.nasa.gov to find local clubs, events, and more!