Download Star Sizes

Star Sizes
The Sun makes up 98% of the mass of the entire Solar System.
If the Sun were hollow we could fit over 1 million Earths inside.
You can line up 110 Earths across the surface of the Sun.
We tend to think of our star, the Sun as being huge. When we compare it to objects here
on Earth, or even Earth itself, it is.
Our star is a medium, sized star. When we compare it to other stars in our galaxy we soon
find compared to other stars it isn’t that big.
First let’s look at the sizes of the planets
Scale models of the planets showing the relative sizes of all 8 planets of our solar system
and Pluto. Earth is not very big by comparison.
Now imaging the size of the Sun compared to Earth or the other planets.
The Sun is considered a medium sized star. It is about 5 billion years old, which means it
is at about half of its useful lifespan.
Now compare the Sun to some other stars, all of which you can see on a good night.
The Sun doesn’t seen so big when compared to these stars.
Sirius is the brightest star in our night sky. The reason for this is that it is relatively close
at only 8.6 light years away. Remember the next nearest star is 4.3 light years away.
Sirius is about twice as massive as the Sun but it is 25 times as luminous.
It can be found in the constellation Canis Major, sometimes called the Dog Star.
Pollux is about 34 light years away and can be found in the constellation Gemini. Pollux
is the brightest star in this constellation. In 2006 it was discovered that Pollux has an
extra solar planet orbiting it.
Arcturus is the 3rd brightest star in the night sky from Northern latitudes. To the naked
eye it appears to be the fourth brightest due to the fact that Alpha Centauri and Proxima
Centauri appear as one star. Arcturus is in the constellation Bootes but the easiest way to
find this star is to follow the handle of the Big Dipper. The handle arc, and if you follow
the arc of the handle the first bright star you see is Arcturus.
Let’s compare our star to a few other well-known stars.
On this scale our star is one pixel in size, too small for us to really see.
Rigel is a blue super giant star estimated to be somewhere between 700-900 light years
away from Earth. Rigel can be found in the lower right of the constellation Orion. Orion
is 17 solar masses and is the brightest star in the Milky Way with luminosity 40,000
times the luminosity of the Sun!
Betelgeuse is another star found in the constellation of Orion. Betelgeuse can be found in
the upper left or Orion. Betelgeuse is a red super giant about 640 light years from Earth.
If Betelgeuse were the star at the centre of our Soar System its surface might extend out
to between Mars and Jupiter!
Antares is the 15th brightest star in the sky. It is more than 1000 light years away