The Sun

An ordinary star, seen up close

You can see it with your eyes

The Sun — The surface of the Sun is not smooth: it boils in grains, with darker spots here and there.

The numbers

What kind of star: Yellow dwarf, type G2 V
Surface temperature: 9,939°F(5,504 °C)
Temperature at the center: 13,600,000K
Share of the Solar System: 99.86%
What it is made of: Hydrogen and helium

To get an idea

The Sun is far bigger than the Moon and far more distant: the two things cancel out, and in the sky the two disks look the same.

The center of the Sun is more than two thousand times hotter than its surface.

Fun facts

These are not in the book: there was no room on paper.

The Sun travels around the center of the Milky Way, about twenty-six thousand light-years away from it.
In about five billion years it will become a red giant and swell beyond the orbit of Mercury.
A star like the Sun takes about ten billion years to use up the hydrogen in its center.
The Sun is almost a perfect sphere: its width at the poles and at the equator differ by about six miles.
The center of the Solar System is not always the center of the Sun, because the planets pull on it.

Test yourself

The first question is the one printed under the QR code, with the answer the book did not give. The other four only exist here.

Question 1 of 5★ is the one from your book

What is the Sun?

Question 2 of 5

What is it mostly made of?

Question 3 of 5

How much of the Solar System is the Sun?

Question 4 of 5

Why do total eclipses happen?

Question 5 of 5

Can you look at the Sun?

Riddles

At my center I squeeze together the lightest things there are, and from that squeeze comes the light that falls on you every morning. I do not burn like a fire. What am I?

I am much bigger than the one that circles you, but also much farther away, so in the sky we look like twins. Every now and then she covers me completely. What am I?

Try it yourself

Activity 1

Mark with a pebble where the Sun sets as seen from your window. Do it again a month later: the spot has moved, and that is what makes the seasons.

Activity 2

Look at the shadow of a pole at noon and look again three hours later. The way it grows longer and turns tells you where the Sun is going.

The words

yellow dwarf: A star of medium to small size and medium temperature, like the Sun.
photosphere: The layer of the Sun that gives off the light we see.

Sources: Wikidata (Q525), Wikipedia (Sole).