Unit Two Science

Astronomy Definition:

Is the study of the stars, moons, planets, galaxies and the universe

The moon turns

once on its axis in about the same time it takes to complete one orbit around Earth. So the same side of the moon faces the Earth

The moon orbits

the Earth once every 27.3 days which is about 1 month

Perigee Definition

is the part of the moon’s orbit when it closest to Earth

Apogee Definition

is the part of the moon’s orbit when it is the farthest from Earth

Since the moon has only a

very thin atmosphere

Impact Theory

Earth was hit by a planet the size of Mars and the debris became the moon

The age of the moon

is believed to be 4-5 billion years old

Since the moon orbits the earth it causes daily chance in its?

appearance from Earth called moon phases

Two reasons for moon phases are

The moon reflects sunlight

The moon orbits Earth

Waxing period

a two week period when the new moon changes into a full moon. The right hand side of the moon is illuminated.

Waning period

a two week period when the full moon changes into a new moon. The left hand side of the moon is illuminated.

How much mass does the sun make up in our solar system?

The Sun makes up 99.8% of mass

Is the sun large compared to other planets

The Sun compared to other stars is not large – it is considered an average yellow dwarf star (found on the main sequence of the H&R Diagram)

What Is the next closest star to the sun?

The next closest star to the sun is Proxima (Alpha) Centauri

How old is the sun?

The Sun is believed to be about 5 billion years old

When is the Sun expected to die?

The Sun is expected to run out of fuel and die in 5 billion years first becoming a red giant then blowing off its outer gasses and becoming a white dwarf. 

How do all stars including the sun get their fuel?

They get their energy from hydrogen fusion

What is the core in the Sun’s layers?

the core is the inner-most layer consisting of hydrogen and helium in plasma state.

Which layer is the visible surface of the Sun?

Photosphere

Which layer is the inner layer of the sun’s atmosphere?

Chromosphere

Which layer is the thin outer layer of the sun’s atmosphere?

Corona