There are about 70 sextillion stars in the universe, including at least 100 billion right here in our Milky Way galaxy. But the star that really matters to earthlings, of course, is the one that lies at the center of our solar system -- our sun.
But how much about this brilliant ball of gas do you really know? Do you have any idea just how big it is? How hot? Or even how old?
Take a look at our list of eight awesome facts to learn something new about the true rockstar of our solar system.
Fact #1. It's even more ginormous than you might have imagined. The sun is so big, in fact, that one million Earths could fit inside it. It weighs a mind-boggling 4,385,214,857,119,400,000,000,000,000,000 pounds, and makes up 99.8 percent of all the mass in the solar system.
Fact #2. It's EXTREMELY hot on the outside -- and thousands of times hotter on the inside. The sun's visible surface, or photosphere, is roughly 10,000 degrees Fahrenheit, while the core's temperature is about 27 million degrees. That's more than 40,000 times as hot as boiling water. The energy produced in the core generates essentially all the heat and light we receive on Earth -- you would need to explode 100 billion tons of dynamite every second to match the sun's energy output.
Fact #3. Copernicus WASN'T the first to place it in the center of our solar system. In fact, Greek astronomer Aristarchus of Samos proposed the first known heliocentric (sun-centered) model in the third century B.C., nearly 1,800 years before Copernicus did.
Portrait of astronomer Nicolas Copernicus, 1580.
Fact #4. It's VERY far away. The sun is 93 million miles from Earth. It takes eight minutes and 19 seconds for sunlight to travel through space and reach us. If it were possible to fly a plane all the way to the sun, the trip would take 26 years, according to NASA.
Fact #5. You'd be really heavy if you walked on the sun. In fact, a person who weighs 150 pounds on Earth would weigh about 4,200 pounds on the sun because the sun's gravity is 28 times that of Earth. Of course, no one is ever going to walk on the sun, as Buzz Aldrin explains in the silly interview with Ali G below.
Fact #6. It's middle-aged. The sun is about 4.6 billion years old now and is expected to last another five billion years before it starts burning helium and expanding into a red giant. At that point it will swallow up Venus, Mercury, and maybe Earth too. It will spend approximately one billion years as a red giant before it shrinks into a white dwarf.
Fact #7. It "flips" every 11 years. When the sun reaches its so-called solar maximum -- its period of greatest activity -- its magnetic field reverses polarity, meaning the north and south pole essentially switch. Scientists observed the field reversal begin in August this year.
Fact # 8. It's something to sneeze at. Achoo! A third of the population experiences what's called the photic sneeze reflex -- sneezing when exposed to sunlight or another bright light. Why does this happen? Aristotle thought it was because the sun warmed the nose. Today scientists think the culprit might be "crossed wires" in the brain -- the trigeminal nerve, which senses irritations in the nose and triggers sneezing, lies close to the optic nerve, which senses light entering the retina. When the optic nerve fires, the trigeminal nerve may pick up those signals and mistakenly activate a sneeze response.