Red, White, and Blue in the Stars!
It's not as explosive as a 4th of July fireworks show, but stars are available for gazing every clear night this month. While there aren't the barrage of colors that we see with fireworks there is red, white, and blue in our July night skies.
Obviously we see white when we look at the stars, but there are also subtle tinges of red, blue, and other shades. We don't see the color in the stars or even planets all that well for two reasons. First of all, planets and stars are so really far away. Planets in our solar system are millions and millions of miles away, and the stars, while much, much larger than the planets, are trillions and trillions of miles away. Not much that light reaches our eyes. When it does, Earth's atmosphere also partially obscures that faint light, even with clear skies.
The second reason we don't see all that color is because of how our eyes coordinate with our brain. We can only take in and process so much light at a time. If we could accumulate light like DSL cameras we would see much more color in the stars. That's why you see a lot more color in astrophotography images.
There is a lot of red to see in the sky this month, compliments mainly of Mars beaming away in the southeastern evening sky. It's still fairly close to Earth at just over 55 million miles away. Not far from Mars is the moderately bright star Antares in the constellation Scorpius. In fact, the name Antares means "rival of Mars". The red we see on 4200 mile-wide Mars is because of an abundance of iron oxide on the surface. The red we see on Antares is because the star is a 6000°F, 760 million-mile-wide ball of hydrogen gas. This super gigantic star is a comparatively cooler star, giving it a ruddy hue. Antares is also a lot farther away than Mars at a distance of over 600 light years, with just one light year equaling nearly six trillion miles. Other cooler stars like Antares also glow red.
By the way, the planet Saturn is just to the left of Mars. It isn't red, but it's a heck of a telescope target even if you have a small telescope. It's my favorite planet outside of Earth.
Another reddish and cooler star in the July evening skies is Arcturus, the brightest actual star in our night sky right now. It's shining high in the southwestern evening and is the brightest star in the constellation Bootes, a farmer hunting down the nearby constellation Ursa Major the Big Bear. It's much easier to see it as what it really looks like though, a giant kite with Arcturus at the tail.
In the eastern heavens there's a good example of a star with a bluish tinge to it. It's Vega, the second brightest star in our summer skies. It sports a slight blue tinge because it's one of the hotter stars in our part of the Milky Way galaxy, with a surface temperature of about 17,000°F. By comparison our sun is about 10,000°F. Vega is part of the "Summer Triangle", made up of three bright stars, the brightest in each of their respective constellations. You can't miss them. They're the brightest stars in the eastern half of the sky right now. Vega is the brightest star in a small faint constellation called Lyra the Harp. Good luck seeing it as that!
Enjoy the red, white, and blue in our July summer skies. Have a great 4th of July!