3.6.9

Light Years

Test yourself

Light Years

A light year is a distance, not a length of time. Light years were first used by the German astronomer Friederich Bassel in 1831.

Illustrative background for Speed of lightIllustrative background for Speed of light ?? "content

Speed of light

  • The light we see from Earth comes from the Sun.
  • It takes 8 minutes 20 seconds for light to travel the 93 million miles between the Earth and the Sun.
    • This means that when we see the sunset, it actually happened 8 minutes 20 seconds before.
  • Light travels at 300,000,000 m/s (sound only travels at 340 m/s!).
Illustrative background for Light yearsIllustrative background for Light years ?? "content

Light years

  • A light year is the distance light travels in 1 year.
  • A light year is 9.5 trillion km.
  • The light from our second nearest star (Alpha Centauri) takes over 4 years to reach us.

Jump to other topics

1Biology

1.1Cells, Tissues & Organs

1.2Reproduction & Variation

1.3Ecological Relationships & Classification

1.4Digestion & Nutrition

1.5Plants & Photosynthesis

1.6Biological Systems & Processes

2Chemistry

2.1Particles

2.2Chemical Reactions

2.3Atoms, Elements, Compounds

2.4The Periodic Table

2.5Materials & the Earth

2.6Reactivity

2.7Energetics

2.8Properties of Materials

3Physics

3.1Energy

3.2Forces & Motion

3.3Waves

3.4Electricity & Magnetism

3.5Matter

3.6Space Physics

4Thinking Scientifically

Go student ad image

Unlock your full potential with GoStudent tutoring

  • Affordable 1:1 tutoring from the comfort of your home

  • Tutors are matched to your specific learning needs

  • 30+ school subjects covered

Book a free trial lesson