Rho Cassiopeioe is one of the very rare yellow hypergiants. They live hard and die fast — our Sun in comparison is much more grown-up and is a hundred times older than the average yellow hypergiants can get. Rho Cossiopeiae is a whopping 3,400 light years away from us. But it’s insane luminosity — 500,000 times that of our Sun — means we can still see it with the naked eye.
The Romans thought the reddish star looked similar to the red planet Mars, which is called Ares in Greek, so they named it Antares, the Anti—Mars. Antares has reached the final stage of its lifespan and will possibly explode within the next ten thousand years. On Earth this would be seen as bright as a full moon that would be visible even during the day for a few months. So let’s root for it to explode soon because that would be cool.
Betelgeuse, aka Orion’s left shoulder, is an unfathomably large red hypergiant star and one of the brightest stars in our night sky. Betelgeuse has a diameter 887 times that of the Sun, and you could fit 700 million Suns inside of it or around a quadrillion Earths. Betelgeuse is rapidly shrinking, and scientists expect it to run out of fuel and go supernova within the next 100,000 years. When it does, it won’t hurt us — it’s on safe 640 light years away — but it will become as bright in our sky as a full moon!
This fatso is 1,420 times the diameter of our Sun. To put that in perspective, if VY Canis Majoris were the height of a 50—story skyscraper, the Sun would be a grapefruit, and the Earth would be a grain of sand 1 mm across.
Mu Cephei leads a sad life. It’s SO close to being the largest known star and a huge celebrity, but it falls just short and now no one talks about it.
And that is all you need to know about stars. Without these omnipresent objects, the universe in its current form would never even exist. Everything you see around you has once been assembled by one of the stars billions of years ago. Every single complex atom of your body used to be in the heart of a star, which was building it for many years by joining lighter elements together. And what is more, all of your atoms, even the atoms of all the other objects on our planet have once been a part of a single star. This massive ancient star eventually exploded as a supernova and ejected its atmosphere into the surrounding cosmos.
The former stellar atmosphere then took the form of a nebula and started collapsing under its own gravitational pull. The Sun was created. Shortly afterwards, the remaining material formed all eight planets of our Solar System, which keep revolving around our parental star to this very day. Almost one billion years thereafter, the first primitive organisms were born. Then, they started evolving diligently for about 3.8 billion years to create me, you and billions of other living organisms that inhabit our beautiful little planet. And all of that was achieved just by using material from a huge ancient star. We could therefore without hesitation proclaim that we come from stars. Literally.
Picture a grain of sand on top of on SUV. That’s what the Sun would look like on top of Stephenson 2—18. If you wanted to fly in a passenger plane around this star once, it would be a 9-million—hour flight — a little over 1,000 years — and even in a lightspeed ship, the journey would take 8.7 hours. And if our home star were Stephenson 2—18 instead of the Sun, it would be bigger than Saturn’s orbit, and Uranus would be the new Mercury.
Stephenson 2—18 was probably born as a main sequence star a few tens of times the mass of the Sun and has likely lost about half its mass by now. While typical red hypergiants are in the ballpark of 1,500 times the size of the Sun, the largest rough estimate places Stephenson 2—18 at an absurd 2,150 solar radii and shining with almost half a million times the power of the Sun.
Stephenson 2—18 is the largest known star… kind of. The tricky thing is, red hypergiants are extremely bright and far away, which means that even tiny uncertainties in our measurements can give us a huge margin of error for their size. Worse still, red hypergiants are Solar-System—sized behemoths that are blowing themselves apart, which makes them harder to measure. As we do more science and our instruments improve, whatever the largest star is will continue to change.
The Kuiper Belt is a donut-shaped region of asteroids surrounding the Solar System, starting just after the orbit of Neptune and ending 20 AU further away. If a hypothetical airplane were flying out of the Solar System, it would take 350 years just to get through the Kuiper Belt! Pluto, no longer a planet, is the largest object in the Kuiper Belt.
If we took all of the DNA in your body and lined it up as a single strand, it would stretch all the way to the Sun and then all the way back to Earth —— 68 times. DNA has a width of about 2.3 nm, which means that if we bunched all of your DNA together into a tight ball, it would be about 108 cubic cm — around the size of a plum.
Launched in 1977, Voyager 1, along with its friend Voyager 2, were the first probes to collect images of the four outer giants of the Solar System. Voyager 2 is still the only probe to visit Uranus and Neptune.
The cool thing about the Voyagers is that even though their original missions are now long over, they’re still zooming outward. They’re both ridiculously far away now and going super fast. Voyager 1 is the faster of the two, going 38,000 mph or 61,000 km/h — so fast that it would cross the Atlantic Ocean in five minutes. It is about 140 AU away from us as of 2020 and was also the first man—made object to leave the Solar System.
Before they launched, a NASA committee loaded them each up with a time capsule — full of symbols, sounds, and images of Earth — so the probes can one day tell aliens what our deal is. Probably a waste of everyone’s time, but who knows.
Keishinrei