Sirius Star Facts #10: The two brightest star(s)?!
Technically, Sirius is a two-star system. In astronomy, this is considered a binary system. We are most familiar with much brighterSirius A, which shines visibly in our night sky. In fact, companion star, Sirius B is around 10,000 times less bright!
Sirius Star Facts #9: Always together, forever apart
Two companion stars comprise the Sirius star system, Sirius A and B. Although gravitationally-bound, the pair lies 20 astronomical units apart. This distance equates to around 1.8-billion-miles. In other words, the same distance between Earth and Uranus
Sirius Star Facts #8: My older brother used to be bigger
Big and bright Sirius A is far larger and brighter than its companion, Sirius B. This is because Sirius A is a main sequence star, one that is still alive and ticking. Whereas, Sirius B is now a white dwarf, much smaller, dimmer and in its twilight years. Billions of years ago, when Sirius B was still in its prime, it would have been the much larger of the two.
Sirius Star Facts #7: Closest white dwarf to Earth
Sirius B is now a white dwarf. During this phase, a very massive star has already stopped generating nuclear fuel, shed its outer layers and become much smaller and dimmer. In fact, Sirius B is currently the closest white dwarf star to Earth.
Sirius Star Facts #6: The “dog star”
“Dog star,” is a common nickname for Sirius. It earned this name by being the brightest (alpha) star in the constellation Canis Majoris, which is Latin for “greater dog.”
Sirius Star Facts #5: One ton of sugar, please!
White dwarfs, are large stars whose mass is smashed into a very small space. Stars that were once millions of miles wide are now only dozens of miles wide as white dwarfs. Because of this, the gravity and density is immense. In fact, a sugar-cube-sized piece of Sirius B would weigh around one ton (2,200 pounds)!
Sirius Star Facts #4: The star so bright, it shines without night
Sirius is extremely bright. Plus, its “near” proximity to Earth amplifies its brightness that much more! Some locations can even observe Sirius during broad daylight! Naturally, city lights are unusually low in these areas.
Sirius Star Facts #3: All of your ancestors saw Sirius
Humans have observed Sirius for centuries. Actually, Sirius comes from the Ancient Greek term for “glowing.” Ancient Egyptian civilizations 4,000 years ago based their calendars on Sirius rising and setting. Even Polynesians civilizations used Sirius as their main navigation.
Sirius Star Facts #2: It will only get brighter
Recent observations show that the Sirius system is slowly approaching our solar system. In fact, during the next 60,000 years the already bright star will only become brighter. Eventually, the system will outshine the likes of Venus and other bright objects!
Sirius Star Facts #1: Smaller but hotter
Being two different types of stars, Sirius A and B have very different attributes. For instance, Sirius A is nearly 1.5 million miles across, whereas Sirius B is only 7,000 miles across. Yet, Sirius A’s surface temperature is around 18,000º F, whereas Sirius B scorches at 45,000º! That’s nearly five times as hot as our Sun!