It is a young, hot-white star only about 8.6 light-years from Earth, and is 25 times brighter than the sun. Compare Sirius to the reddish Betelgeuse, which is the upper right shoulder of Orion, the hunter, and is just to the northwest of Sirius.

Albus Percival Wulfric

Sirius, also called Alpha Canis Majoris or the Dog Star, brightest star in the night sky, with apparent visual magnitude −1.46. It is a binary star in the constellation Canis Major. The bright component of the binary is a blue-white star 25.4 times as luminous as the Sun.

Closest Stars to Earth

1. Sun. 0.0000158.
2. Proxima Centauri. 4.2421.
3. Alpha Centauri (binary star) 4.3650.
4. Barnard’s Star. 5.9630.
5. Wolf 359. 7.7825.
6. Lalande 21185. 8.2905.
7. Sirius (binary star) 8.5828.
8. Luyten 726-8 (binary star) 8.7280.

Pistol Star

Alpha Centauri A & B are roughly 4.35 light years away from us. Proxima Centauri is slightly closer at 4.25 light years.

The closest star to Earth are three stars in the Alpha Centauri system. The two main stars are Alpha Centauri A and Alpha Centauri B, which form a binary pair. They are an average of 4.3 light-years from Earth.

When the star is low in the night sky, the star’s light must travel through more of the Earth’s atmosphere to reach our eyes. The atmosphere refracts the star’s light, similar to how a crystal creates a rainbow effect with the sunlight. So we see Capella’s light as red and green flashes.

Turbulence in the atmosphere causes the “twinkling” or seeing. Because the color perception in the human eye doesn’t work in faint light, this colorful twinkling is observed for the brightest stars only. The doppler shift is not the reason for the red and blue colors.

In simple terms, twinkling of stars is caused by the passing of light through different layers of a turbulent atmosphere. Most scintillation effects are caused by anomalous atmospheric refraction caused by small-scale fluctuations in air density usually related to temperature gradients.

Watch the sky closely in the dawn or dusk hours, and you’ll likely see a moving “star” or two sliding by. These are satellites, or “artificial moons” placed in low Earth orbit. These shine via reflected sunlight as they pass hundreds of kilometres overhead.

By some estimates, hundreds of Starlink satellites could be constantly visible in the night sky from any location on Earth. This could ruin the natural beauty of the night sky, and make astronomy much more difficult. Currently there are no laws or regulations that protect the aesthetic of the night sky.