Light & Speed
What is the speed of light in space?
299 792 458 meters per second (3 × 10⁸ m/s)
What is a light year a measure of, distance or time?
Distance
What is the Big Bang?
The beginning and expansion of the universe
What is redshift?
Light stretched toward the red end as an object moves away
How old is the universe estimated to be?
About 13.8 billion years
What letter do scientists use for the speed of light?
C
How far does light travel in one year?
9.46 trillion km
What happened at 0 seconds?
The universe began expanding from a hot, dense point
What everyday effect is similar to redshift?
The Doppler Effect
Name one way astronomers estimate its age.
Looking for the oldest stars or measuring the expansion rate
OR
By measuring the rate of expansion of the universe and extrapolating back to the Big Bang
Why can’t anything with mass travel at light speed?
It would require infinite energy
How long would it take humans to travel one light-year with current tech?
About 37 200 years
What formed in the first few minutes?
Protons, neutrons and electrons
Who discovered galaxies are moving away from us?
Edwin Hubble
What does expansion suggest about the universe’s past?
It was once smaller and hotter
Does the speed of light change when different people are measuring it ?
No
Why do astronomers use light-years instead of kilometres?
Because space distances are enormous
How long after did atoms first form?
Around 380 000 years
What does redshift tell us about the universe?
It’s expanding
What evidence besides redshift supports the Big Bang?
Cosmic Microwave Background radiation
If light travels at 300 000 km/s, how far does it go in 2 seconds?
600 000 km/s
If a star is 4 light-years away, how long does its light take to reach us?
4 years
What formed millions of years later?
Stars and galaxies
If a galaxy’s light is very red-shifted, what does that mean?
It’s farther away and moving faster
If the universe is still expanding, what can we say about its future?
It will keep expanding (and cooling) over time