OUTER space is extremely distant yet so close.
It would take just over an hour to drive to outer space at highway speeds but the nearest celestial object, the Moon, is about 239,000 miles away.
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The Moon is illuminated by light rays coming from the Sun and reflecting onto the Earth’s surface.
Visible light rays travel at 186,000 miles per second, meaning light needs more than one second after it’s been reflected off the Moon’s surface to travel to Earth.
As a result, the version we see of the Moon from Earth is actually what it looked like roughly 1.3 seconds prior.
In this sense, you’re actually looking back in time every time you look at the Moon without even realising it.
This principle is observable in Nasa’s communications with the Apollo astronauts that traversed the moon.
Radio waves travel just as fast as the speed of light.
Radio communications between the control center in Houston, Texas and the astronauts feature 2.5 second delay between correspondences–1.25 seconds for speech to reach the astronauts and 1.25 seconds for their response to return to Earth.
Scientists are applying the concept of “old light” to study distant space using the James Webb Space Telescope.
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Any light that reaches the telescope may be the last trace of a star that exploded long ago.
The telescope may also unearth mysteries about the expansion of the universe.
The telescope can measure the distance between two stars and determine how fast they are moving apart or toward one another.
Light travels extremely fast, but the expanse of space is so large that it takes several seconds or even minutes for light from within our solar system to reach Earth.
A lightyear–the distance light travels in one year–is roughly one trillion miles.
Light from the Sun needs over eight minutes to reach Earth.
The nearest galaxy comparable to the Milky Way is the Andromeda Galaxy 2.5million lightyears away.
If there is intelligent life in Andromeda viewing us here on Earth, their observations are of our planet 2.5million years in the past.
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