The Sun

ASSIGNMENT #41

The word "solar" is taken from the Latin word for sun, Sol.

Solar System: a large planetary system that consists of a combination of many smaller planetary systems and objects.

2 factors that keep planets orbiting around the sun:

1. Inertia – the resistance an object has to a change in its state of motion. The more mass an object has, the more inertia it has.

2. Gravity – force that holds planets in orbit around the sun.

The sun’s gravity is so strong because the sun’s MASS is very large. 99.8% of the mass of the entire solar system is in the sun!

Why aren’t we pulled into the sun?

The planets are in orbit around the sun because the sun’s gravity pulls on them while their inertia keeps them moving ahead.

Let’s consider how changing inertia and/or gravity would affect the position of a planet in space…

What would happen if the gravity of the sun, for example, increased?

What would happen in the gravity of the sun, for example, decreased?

What would happen in the inertia of the Earth, for example, increased?

What would happen if the inertia of the Earth, for example, decreased?

How big is the sun?

Solar flareAbout 1 million Earths could fit inside the sun

Characteristics of the Sun:

Has an interior and an atmosphere.

Does not have a solid surface.Is a ball of glowing gas.About ¾ of the sun’s mass is

hydrogen (H), ¼ is helium (He) and very small amounts of other chemical elements.

Why are there stars (such as the sun)?

They are the result of constant nuclear fusion:

H + H He

Heat energyLight energy

What is the source of a star’s energy?Nuclear Fusion: hydrogen atoms join together to form helium

H + H He

Heat energyLight energy

Where does this nuclear fusion occur in a star (such as our Sun)?

H + H

in the core…

HeHeat energyLight energy

What is the core of any star (such as the Sun)?

It’s the innermost part of the star where fusion occurs. When the energy source of the Sun, its H, is “used up,” the Sun will no longer give off heat or light energy. It will “die.”

Nuclear fusion occurs only under conditions of extremely high temperature and pressure. The temperature inside the sun’s core, or center, reaches about 15 million degrees Celsius, high enough for nuclear fusion to occur.

How old is our sun?

Our sun is about 5 billion years old. It is believed that the sun will last about another 5 billion years.

The core is the ‘part’ of the sun in which fusion occurs, so it’s like the “birthplace” of the star… What is the rest of the sun made of?

Layers of atmosphere

The sun’s visible layer, the photosphereis the layer of gas that we ‘see.’ When you look at an image or photograph of the sun, you are looking at the photosphere.

The Greek word photo means “light,” so photosphere means the sphere that makes light.

This photo shows the red chromosphere, which is the layer above the photosphere.

The Greek word chromo means “color,” so the chromosphere is the “color sphere.”

This photo of the chromosphere was taken with a special camera, so you can clearly see that it is a red layer that completely surrounds the sun. In this photo, you can also see the brighter photosphere ‘peeking through.’

You can see the very faint, usually invisible outer layer of gas calledthecorona. Do you see what appears to be a halo or crown?

What are some of the features of the sun?

Prominence

SunspotsSolar Flare

What do sunspots really look like (close-up view)?

What are sunspots?

Sunspots

Are they darker or lighter than the rest of the Sun?

Do you think that they are areas that are cooler or warmer than the rest of the Sun?

Sunspots usually occur in pairs or groups. Reddish loops of gas called prominences link different parts of sunspot regions.

Prominence- arching

of gases o

n the su

n

Solar flare- sudden temporary outburst of energy from a small area of the sun's surface.

Sometimes the loops in sunspot regions suddenly connect, releasing large amounts of energy. The energy heats gas on the sun to millions of degrees Celsius, causing the hydrogen gas to explode out into space. These explosions are known as solar flares.