Grade 9 Astronomy Test

Hottest planet

Hottest planet

Venus

Largest planet

Jupiter

Smallest planet

Mercury

Planet with thin carbon dioxide atmosphere

Mars

Planet with visible rings

Saturn

Solar eclipse

Occurs when the Moon passes directly between the Sun and Earth and casts a shadow over part of Earth

Lunar eclipse

Occurs at a full moon when Earth is directly between the moon and the sun

What causes high tides?

• The gravity of the moon pulls the water towards it, causing a bulge or a rise in the sea level, which results in high tide

• This occurs on two sides of the earth

What causes low tides?

• In contrast to high tides, the parts of the Earth's oceans that are furthest away from the moon experience a weaker pull due to water receding and going to a high tide

• This results in the sea level dropping, which causes a low tide.

Rocky Planets (in order)

Mercury, Venus, Earth, Mars

Gaseous Planets (in order)

Jupiter, Saturn, Uranus, Neptune

Meteoroid

A chunk of rock or dust in space

Meteor

A streak of light in the sky produced by the burning of a meteoroid in Earth's atmosphere.

Meteorite

A meteoroid that passes through the atmosphere and hits Earth's surface.

What is the sun made of?

75% hydrogen and 25% helium

Solar flare

A sudden eruption of intense high-energy radiation from the sun's surface

Sunspot

A cooler darker spot appearing every 11 years on the sun's photosphere

Aurora

An atmospheric phenomenon consisting of bands of light caused by charged solar particles following the earth's magnetic lines of force

How do seasons occur?

• Caused by the tilt of Earth's axis

• If the axis is tilted away from the Sun, that hemisphere is in the winter, because it is receiving less direct sunlight

• If the axis is tilted towards the sun that hemisphere is in summer and is receiving direct sunlight

Comets

Balls of ice, rock, and dust in space with a tail

Why do comets have tails?

When they come to the inner part of the solar system, the sun vaporizes some of them leaving behind a tail.

What is an asteroid?

A rock orbiting the Sun that was left over when the planets formed.

Where is the asteroid belt located?

Between Jupiter and Mars

What is the heliocentric model?

The sun is the center of the solar system

Earth's rotation period

24 hours

Earth's revolution period

365 days

Big Bang Theory

The theory that the universe originated from an infinitely small and infinitely hot mass in a huge explosion that released all matter and energy.

Solar Nebula Theory

The theory that describes how stars and planets form from contracting, spinning disks of gas and dust

Light years

The distance light travels in a year

What are constellations?

Groups of stars that make an apparent pattern in the sky.

What are ways to classify stars?

• Temperature

• Colour

• Luminosity

• Mass

• Radius