Non-fiction – Keishinrei

Distance from the Sun to Earth

To visualize how far away the Sun is, think about it like this: the Sun is 100 Suns away from us. So if the Sun were a basketball, you could imagine lOO basketballs lined up, and that’s how for away the Sun would be. This distance is known as an AU, or Astronomical Unit. If planes could fly through space, going to the Sun would be an 18—year flight.

We can also use the AU to visualize the size of the Solar System. Mercury, Venus Earth and Mars are 1/3, 2/3, 1 and 1.5 AU from the Sun. Jupiter is 5 AU away while Saturn, Uranus, Neptun and Pluto are conveniently about 10, 20, 30 and 40 AU from the Sun, respectively.

Enif

Enif is a massive dying star, which doesn’t mean it is calmly enjoying the rest of its old age. Enif — or Epsilon Pegasi — is known for its erratic and violent behavior. In 1972, the star was observed to release some kind of enormous flare, five times brighter than normal. These kinds of events are only poorly understood and only about 24 of them are documented, so we don’t know what irritated it. But if we were constantly stalked by gawking researchers we’d probably be grumpy too.

Deneb

A blue-white supergiant in the constellation Cygnus, Deneb is over 50,000 times brighter than the Sun. It’s pretty far from us though — 2,615 light years — so it’s only the 19th brightest star in our sky.

Perspective About the Cosmos – Introduction

People are quite good at estimating various things. To demonstrate what I mean, try answering the four following questions. How long does it take an average person to walk half a kilometre? Approximately how many eggs fit into small box? How much taller is an adult person compared to a six-year-old? What is the average difference in temperature between summer and winter? It is very likely that your answers to the questions above were to some extent correct.

Everybody knows that an ordinary human walks a distance of a few hundred meters in a couple of minutes, that about five to ten eggs fit into a small box, that a child is about two or three times smaller than an adult, and that the difference between summer and winter temperatures is several dozen degrees at most. No reasonable person would tell you that they can walk half a kilometre in about a tenth of a second, that about a billion eggs fit into a box, that a twenty-year-old is about a hundred thousand times larger than a child or that the temperatures in summer can be up to a million times greater than those in winter. Our brains are excellent at estimating these things, since we encounter them on a daily basis.

But once we get over the border of the ordinary world, our perspective suddenly vanishes. How many atoms fit into the dot of the question mark at the end of this sentence? How much farther from Earth is the Sun compared to the Moon? What is the difference in temperature between the Sun’s core and its surface? If you have not happened to learn the answer to one these questions, you might not be able to respond. And if you have at least tried, it is very likely that your answer is far off from reality. Our brains do not encounter atoms or stars on a daily basis, which makes answering these questions immensely difficult for them. The aim of this chapter is therefore to bring a little bit of perspective into the mysterious world of the cosmos.

Pistol Star

This blue hypergiant with the catchy name is one of the brightest stars in the Milky Way and led the list of the largest stars for a while. Unfortunately, it can’t be seen with the naked eye since it is hidden behind interstellar dust. The brighter a star is, the more mass it ejects constantly, and every 20 seconds the Pistol Star radiates as much energy as the Sun does in one year.

Rho Cassiopeiae

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.

Antares

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

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!

VY Canis Majoris

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

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.