The month of February signals the last full month of winter. Despite that, though, this is the perfect time during which to view the winter sky, which features some of the brightest and hottest stars within ,1,000 light years of Earth. So, while the nights may be cold, the stars are anything but at this time of year.
When looking at the stars, color is a direct measure of brightness. On Earth, the term “red-hot” is often used to describe something of extreme temperature. With stars, though, red is actually signifies the coolest stars. In descending order of temperature, these are the stellar colors to look for: blue, blue-white, white, yellow, orange, and red. Now, taking a walk outside and looking to the sky on a February night, one cannot notice all of the hot blue stars populating the sky at this time of year.
So, why is this?
Because we live in it, it is impossible to tell exactly what our Milky Way Galaxy looks like. However, from both observations of what types of stars are located where in the sky and by looking at other, similar galaxies, scientists can give an educated guess as to what our island universe in the cosmos looks like. The picture: a barred spiral galaxy with old stars at the center and young ones in the outer arms. Now, for reasons not fully understood, the outer arms of the galaxy tend to be populated wit hot, young, blue stars while the galactic center teems with older, yellow and cooler stars, the big blues having long since gone supernova. Why more blue stars haven;'t formed is anyone's guess but, as far current observation has determined, if one wants to see hot, young, blue stars, one has to look toward the outside of the galaxy, which is just what we happen to be doing this time of year.
Like with the constellations, certain sections of the galaxy are visible at some points of the year and not others because the Sun is in the way. Example, right now, we just happen to be facing toward the outer edges of the galaxy while it is night. During the day, we face the galactic center, the dense old stars, and the ghostly stellar river that is the Milky Way itself, which is why we cannot see it as the Sun's glare blocks out everything in this area of sky. In summer, the situation is flip-flopped.
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