Episode 4: A Sky Full of Ghosts Flashcards
Explain how the night sky is full of ghosts?
Every star is as big and bright as our own star, the sun. Light travels fast but not infinitely fast. It takes time for the light from the stars to reach us. For the nearest stars ones it takes eons to reach earth. By the time the light reaches earth some stars are already dead
Who was the first person to understand that a telescope is a time machine?
William Hershel was the first person to understand that a telescope is a time machine. We cannot look into space without seeing back in time
How far does light travel in 1 second?
In 1 second light travels 300,000kms
How far away is the moon from the earth?
The moon is just over 300,000kms from earth so it is 1 light second from earth. Whenever we look at the moon we are seeing it one second in the past
Why is the sunrise an illusion?
The earths atmosphere bends the suns light like a lens or a glass of water. We see the image of the sun projected on the horizon before the sun is actually there
How long does light take to get from the sun to earth?
Sunlight takes about 8 minutes to reach earth so the sun is 8 light minutes from earth. From earth we can only see the sun as it was 8 minutes ago
How far away is neptune from earth?
Neptune is 4 light hours away from earth. We can only view neptune as it was 4 hours ago
How far is a single lightyear in kilometres?
A single lightyear is nearly 10 trillion kms
What is the nearest star to the sun and how far away is it?
The nearest star to our sun is Proximus Centuri and it is a little more than 4 lightyears away
How fast does voyager travel?
Voyager travels at more than 56,000kms per hour. It will take voyager 80,000 years to reach the nearest star
How far away is the Pleiades Cluster?
The Pleiades Cluster is approximately 400 lightyears away
What is the Crab Nebula?
The Crab Nebula was once a giant star 10 times the mass of the sun. It exploded as a supanova and now at its heart is pulsar, a collapsed star the size of a city spinning 30 times a second. It’s magnetic field excites electrons around it accelerating them to almost the speed of light which makes them shine with a blue glow. The Crab Nebula is 6500 lightyears away from earth
How far away is the earth from the centre of the galaxy?
The centre of the galaxy is 30,000 light years from earth
How old is the light we can see from the Sombrero galaxy?
The light we can see from the Sombrero galaxy is 30 million years old
How far away from earth is the Coma Cluster?
The Coma Cluster is 320 light years away
What is the oldest light we have ever detected in our universe?
The oldest light we have ever detected is 13.4 billion years old detected by the Hubble telescope