When we are looking at light from space we are looking into the past Why is this?
When we are looking at light from space we are looking into the past Why is this?
When we use powerful telescopes to look at distant objects in space, we are actually looking back in time. How can this be? Light travels at a speed of 186,000 miles (or 300,000 km) per second. This seems really fast, but objects in space are so far away that it takes a lot of time for their light to reach us.
What does it mean to say that the farther out we look the further back in time we look?
3) Explain the statement The farther away we look in distance, the further back we look in time. The time it takes for light to reach earth can be considered along the lines of a time delay, thus we are looking back into history. The longer the delay, the further back in time we are looking.
Why can we see further back in time when an object is farther from us?
Because light takes time to travel from one place to another, we see objects not as they are now but as they were at the time when they released the light that has traveled across the universe to us. Astronomers can therefore look farther back through time by studying progressively more-distant objects.
What does cosmological redshift do to light?
The universe is expanding, and that expansion stretches light traveling through space in a phenomenon known as cosmological redshift. The greater the redshift, the greater the distance the light has traveled.
What do you understand by the term light-year?
Light-year is the distance light travels in one year. Light zips through interstellar space at 186,000 miles (300,000 kilometers) per second and 5.88 trillion miles (9.46 trillion kilometers) per year.
What does lookback time mean?
The time elapsed between when we detect the light here on Earth and when it was originally emitted by the source, is known as the ‘lookback time’. The more distant an object is from us, the further back in time we are looking.
How many light-years away is another universe?
46.5 billion light-years
The comoving distance from Earth to the edge of the observable universe is about 14.26 gigaparsecs (46.5 billion light-years or 4.40×1026 m) in any direction. The observable universe is thus a sphere with a diameter of about 28.5 gigaparsecs (93 billion light-years or 8.8×1026 m).