DISTANCE
1. WHAT IS THE DISTANCE OF THE SUN FROM THE EARTH?
Ans: The distance of the Sun from Earth varies between 91 and 94 million miles.Astronomers can measure the distance very accurately by bouncing radar waves off the planets.
2. WHAT IS RED SHIFT?
Ans: When a galaxy is moving rapidly away from us, the waves of light become stretched out – that is, they become redder. The greater this red shift. the faster the galaxy is moving away from us.
3. WHAT IS A LIGHT-YEAR?
Ans: A light year is 9,460.000.000.000 km. This is the distance light can travel in a year, at its constant rate of 300,000 km per second.
4. HOW FAR IS IT TO THE NEAREST STAR?
Ans: The nearest star is Proxima Centauri, which is 43 light-years away, or 40 trillion km.
5. WHAT IS A PARSEC?
Ans: A parsec is 3.26 light-years. Parsecs are parallax distances- distances worked Out geometrically from slight shifts of a
star’s apparent position as the Earth moves around the Sun.
6. HOW DID ASTRONOMERS FIRST ESTIMATE THE SUN’S DISTANCE?
Ans: In 1672, two astronomers, Cassini in France and Richer in Guiana, noted the exact position of Mars in the skies. They could work out how far away Mars is from the slight difference between their two measurements. Once they knew this, they could work out by simple geometry the distance from Earth to the Sun, Cassini’s estimate was only a few percent out.
7. WHAT IS THE FURTHEST OBJECT WE CAN SEE?
Ans: The furthest objects we can see in space are quasars,which may be over 13 billion light-years away.
8. ARE THE STARS GETTING FURTHER AWAY?
Ans: Analysis of red shifts has shown us that every Single galaxy is moving away from us. The further away the galaxy, the faster it is moving away from us. The most distant galaxies are receding at almost the speed of light.
9. HOW FAR AWAY IS THE MOON?
Ans: At its nearest, the Moon is 356.517 km away from Earth; at its furthest, it is 406,71| km away. This is measured accurately by a laser beam bounced off mirrors left on the Moon’s surface by Apollo astronauts and Soviet lunar probes. The distance is shown by how long it takes the beam to travel to the Moon and back.
