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In about 5 billion years, the Sun will die a spectacular death.
As its hydrogen runs out, it will begin to burn helium. The Sun will become a red giant, stretching out to where Venus orbits today. Once the helium is used up, the Sun will collapse. It’ll become a hot white dwarf star about the size of Earth. Then it will cool.
We know all this from watching other stars. Point a telescope in just about any direction, and you’ll see some star’s birth or death in progress. Recently, scientists have discovered that some stars have planets spinning around them, just as our star does. Perhaps somewhere, there’s a planet where creatures are wondering, “Who’s out there?”
Supernovas
▲ The fireworks surrounding the Sun’s death will be tiny compared to what happens when a larger star dies. When massive stars run out of fuel, they explode. This turns them into supernovas. For a few days, they produce as much light and heat as an entire galaxy. In 1054, Chinese astronomers saw a supernova so bright that it was visible during the day.
Nebulas
Nebulas are clouds of gas, dust, and ice in space. They often form after supernova explosions and become hatcheries for new stars. In fact, scientists believe the Sun is a recycled star. That’s because it contains heavy elements such as iron that aren’t always found in live stars. That means the gas cloud out of which it formed was the remains of previous stars that had died out.
▲ Even if there is life elsewhere in the universe, we may never find it. Distances in space are so vast that they’re measured in light-years. A light-year is the distance that light can travel in one Earth year. Light travels about 186,000 miles per second. That’s about 6 trillion miles per year. The closest star to our Sun is Proxima Centauri, about 25 trillion miles away. The light we see from Proxima Centauri takes roughly four years to reach us, which means it’s about four light-years away.
◀ Much of what we know about the universe began with Galileo Galilei (1564–1642). He was the first person to study the universe using a telescope. He’s also famous for proving Copernicus’s theory that Earth goes around the Sun, not vice versa. For this, he was tried by the Inquisition in Rome. He spent the last eight years of his life under house arrest. He went blind when he was an old man. This was caused in part by looking at the Sun without eye protection.
Check It Out!
Where do stars go during the daytime?
The stars are still in the sky, but the Sun is so bright that it blots out their light.
Sun Fact
Rotation
27 days at equator, 30 days at poles. They differ because the Sun’s gases move at different speeds.
Pulsars
When a giant or supergiant star explodes, it faces one of two fates. If it collapses completely upon itself, it becomes a black hole. That’s where objects are sucked in, stretched to infinity, and get trapped forever. Or it might become a pulsar. That’s a rapidly spinning neutron star. When first discovered, the pulses of light coming from pulsars seemed like messages from aliens. Scientists half-jokingly labeled them LGMs—Little Green Men. ▼
This is an X-ray view of the Crab Nebula. You can see a spinning pulsar at its center. This nebula is what’s left of the supernova the Chinese astronomers saw in 1054.
Here are three other views of the Crab Nebula.
