SUN

It's a large ball of gas, a gaseous sphere.

It's not a solid, but is a ball of gas.

Made mostly of gases-Hydrogen and Helium

held together by gravity

It's 100 times larger than earth

The sun's outer atmosphere

You can only see it during a total eclipse

because the gases are so thin

This region of the sun is just below the corona and above the photosphere. Like the corona it too is invisible unless there is a solar eclipse.

It's 3,000 km thick

The sun's surface

This part of the sun is the part we can see

Because the gases are thick enough.

it is about 600km thick

This region of the sun is below the photosphere.

200,000km thick

where gases circulate

where hot gases rise

and cooler gases sink toward the interior (inward)

This region/zone of the sun is very dense

about 300,000km thick

the atoms in this zone are so closely packed that light can take millions of years to pass through.

This is the center of the sun

Hottest part of the sun 15,000,000 centigrade

it's where the sun's energy is produced-

(where nuclear fusion happens)

the center of the sun has a radius of 200,000km

The layers of the sun (C-C-P-CZ-RZ-C)

Corona - (outer atmosphere)(invisible)

Chromosphere- (also invisible)

Photosphere- (surface-we can see)

Convective zone- (thick gases circulate)

Radiative zone- (very dense)(closely packed atoms)

Core- (center)(where energy is produced-nuclear       fusion)

Through a process called nuclear fusion in the sun's core

SOLAR ACTIVITY-

The circulation of gases within the sun's convective zone + the sun's rotation produces magnetic fields, which causes areas on the photosphere to be slightly cooler than the surrounding areas. These cooler ares show up as sunspots

The process by which 2 or more small nuclei(like hydrogen) join together(fusing) to form a larger more massive nucleus (helium)then energy is produced

E=mc2 (Energy=mass x speed of light)

Changes in the magnetic properties of the sun cause

_____________and _____________

Before scientists figured out nuclear fusion was how the sun produces energy they used to think:

1-the sun was burning & that was how it released energy

2-then later they thought it was shrinking due to gravity and that would release enough energy.

-to learn what earlier galaxies looked like

-to see how galaxies change over time

-get an idea how/what caused them to form

Cosmology

the study of the universe's origin, structure and future

Big Bang Theory

The ___ ___ ___ states the universe began with an explosion about 13.7 billion years ago

Astrophysicists NOW think that there is not enough matter in the universe to stop it expanding outward, so the universe will

gravity

what holds a galaxy together

Cosmic background radiation

(left over radiation from the Big Bang)

the radiation comes from all directions

What is supporting evidence that the Big Bang happened

1-by measuring the distance to the farthest galaxies.

2- by calculating the age of nearby stars

Universal Expansion