The Sun

The central object of our solar system and the closest star to Earth, where hydrogen atoms are fused into helium, releasing massive amounts of energy.

Terrestrial Planets

Dense and solid planets closest to the Sun.

Gas Planets

Giant gaseous planets farthest from the Sun.

Mnemonic Phrase

A phrase used to remember the order of the planets, such as 'My Very Elderly Mother Just Served Us Noodles'.

Mercury

The planet with no atmosphere and many craters caused by meteorites.

Venus

The planet with a thick, mostly carbon dioxide atmosphere, causing a greenhouse effect and high temperatures.

Earth

The largest terrestrial planet, mostly covered in water and known to have life.

Troposphere

The layer of Earth's atmosphere where weather occurs.

Stratosphere

The layer of Earth's atmosphere that contains the ozone layer.

Mesosphere

The layer of Earth's atmosphere that burns up meteors.

Thermosphere

The outermost layer of Earth's atmosphere.

Mars

The 'Red Planet' with a carbon dioxide atmosphere and evidence of past water.

Jupiter

The largest planet with continuously changing colored bands of gas and a giant storm called the 'eye'.

Saturn

The planet surrounded by large rings of rock and ice and is less dense than water.

Uranus

A blue-green planet made of hydrogen, helium, and methane with less visible rings.

Neptune

A planet with atmosphere made of methane, very cold and windy, and 30 times farther from the sun than the Earth.

Natural Satellites

A celestial body, commonly called moons, orbit planets as the planet orbits the Sun.

Comets

A large ball of snow, ice, rock, and dust that is flying through space and has a tail that always points away from the Sun.

Asteroids

Larger rocky body, without an atmosphere, that travels through space, without leaving a tail.

Meteorites

Small rocky/dust fragment from comets or asteroids that burn and break apart when they enter the Earth’s atmosphere, creating shooting stars.

Rotation

The daily spinning of the Earth on its axis, causing day and night.

Revolution

The annual travel of the Earth around the Sun, taking 365¼ days to complete and leading to leap years.

Winter Solstice

The shortest day of the year in the Northern Hemisphere, when the North Pole is most tilted away from the Sun.

Equinox

Occurs on March 21st and September 23rd, when the North and South Poles are both equal distance to the Sun, and day and night each last 12 hours.

Summer Solstice

The longest day of the year in the Northern Hemisphere, when the North Pole is most tilted towards the Sun.