space

Question

Answer

What is our solar system made of

The Sun 8 planets dwarf planets moons asteroids comets

What is a galaxy

Huge collection of billions of stars held together by gravity Our galaxy = Milky Way

What is the universe

All existing matter and energy billions of galaxies

How do stars form

From nebula cloud of gas dust pulled together by gravity heats up nuclear fusion starts

Life cycle star same mass as Sun

Nebula → Protostar → Main sequence → Red giant → White dwarf → Black dwarf

Life cycle star much bigger than Sun

Nebula → Protostar → Main sequence → Red supergiant → Supernova → Neutron star or Black hole

What is main sequence star

Longest stable stage gravity balanced by fusion energy output

What is red giant

Star runs out of hydrogen expands cools turns red

What is white dwarf

Remnant of small star hot dense no fusion left to cool

What is supernova

Massive star explodes at end blasts elements into space

Orbital motion basics

Planets moons satellites move in nearly circular paths speed constant velocity changes direction changes

What provides centripetal force

Gravity always pulls towards centre keeps object in orbit

Orbit rules if speed increases

Object moves faster needs smaller radius to stay stable

Orbit rules if speed decreases

Needs larger radius otherwise falls inwards

What is natural satellite

Object orbiting planet not man made examples Moon

What is artificial satellite

Man made orbit Earth communications weather GPS

What is red shift

Light from distant galaxies shifted to longer red wavelengths

What does red shift show

All galaxies moving away from us further = faster moving

What is Big Bang theory

Universe started from tiny hot dense point expanded ever since

Evidence for Big Bang

Red shift cosmic microwave background radiation CMBR

What is CMBR

Leftover heat radiation from early universe found everywhere