Block 1 Lesson 4

Components of the Solar System

Celestial equator

The imaginary projection of Earth’s equator. It divides the celestial sphere into the northern and southern hemisphere.

Celestial sphere

An imaginary, Earth-centered sphere which all celestial objects are projected in.

Ecliptic

The apparent path of the Sun throughout the course of a year. 👍

An imaginary line which shows where the Sun appears to be in sky. sort of...?

Elliptic

The shape of an astronomical object’s orbit around the another astronomical object, elongated circle shaped.

Parts of a comet

• Nucleus

• Coma

• Hydrogen envelope

• Dust tail

• Ion tail

Nucleus

• The centre of the comet

• Made of ice, dust and rocks

Coma

• Envelopes the nucleus

• A dense cloud of water, carbon dioxide and other neutral gases sublimed (solid to gas)

• More ice, dust and rocks

Hydrogen envelope

• Huge (millions of km in diameter) but very sparse cloud of neutral hydrogen

Dust tail

• Always opposite the sun

• Made of dust particles driven off the nucleus

• Up to 10 million km long

• Broader than ion tail

Ion tail

• Forms behind a comet as it approaches the Sun

• Made of ionised gases

• As much as several hundred million km long

Do comets orbit?

Ofc they do, they orbit the Sun (in very elliptical orbits, search up an image, it’s cool)