1. One light year is equivalent to 5.9 Trillion miles.
2. There are more planets in the universe than there are grains of sand on all the beaches of the Earth.
Let that sink in, then continue reading. Every single point of light in this picture is an entire galaxy, each galaxy contains approximately 200 billion Suns. The image is called the “Hubble Ultra-Deep Field”. It is the farthest we’ve ever seen into the Universe. This picture is mind numbing if you can understand what you’re actually seeing.
Imagine for a moment that you’re outside on a clear night with a full moon. You take a quarter, close one eye and hold the quarter at arms length. The quarter can just about block out the moon. Now imagine replacing the quarter with a single grain of sand. The amount of sky that is “blocked out” by the grain of sand is the size of the patch of sky at which the Hubble was pointed. There are 3,000 galaxies in that picture. 3,000 galaxies in a patch of sky no bigger than a grain of sand held out at arms length. Every single dot, smear, and smudge is an entire galaxy. The enormity of the Cosmos is such that our minds are not wired to envision those distances. In fact, we have to measure it in light-years. Kilometers or miles are no good on the cosmic scale. To measure the distance from Earth to any star in miles would be more futile than measuring from NYC to New Zealand in millimeters.
What is a light-year? It is the distance that light travels in one year. ONE LIGHT-YEAR = 5.9 TRILLION MILES. Let’s put this in perspective. At the equator, the Earth is about 25,000 miles in circumference. The moon is 253,000 miles away, on average. The Sun, which is 880,000 times the size of the Earth, is 93 million miles away. The nearest star to Earth other than the sun is 4.2 light years away. That’s 24 TRILLION MILES. The Milky Way Galaxay in which we live is about 100,000 light-years across. The Milky Way has 250 billion stars, of which the Sun is just one. The observable universe has about 100 billion galaxies, some containing more than one trillion stars. Most of the stars in each galaxy have planets caught in their gravitational embrace, just like our sun. The general consensus among Cosmologists and Astronomers is that there are more planets in the universe than there are grains of sand on all the beaches of the Earth.
Another way to attempt to put the prodigious cosmic scale into perspective is to think about the fastest vehicle mankind has ever made. Voyager 1 is a space probe launched in 1977.
We continue to receive a signal from it, though its mission ended 20 years ago. It flew past all the planets of the solar system and is responsible for all those beautiful and famous close up pictures of the planets. Voyager then continued out past Pluto and has been careening through the void of empty space at 11 miles per SECOND. It is roughly 12 billion miles from Earth and in 2014, it entered interstellar space. Interstellar is defined as the space between the stars. It is the fastest man made object of all time. It is also the farthest we’ve ever sent anything. There is no air resistance in space, so Voyager continues unimpeded in that frictionless environment, at that speed, forever.
As it relates to cosmic distance, Voyager will not reach the nearest star for 25,000 years, despite the fact that it’s moving 12 times faster than a bullet fired from a high powered rifle. At 38,610 mph, Voyager will take many tens of millions of years to get to the other side of the galaxy.
It has been said that this picture is the most important image of all time simply because it reminds us to be humble. We are small players in a vast cosmic arena. That picture proved that the universe is impossibly large. It toned down the human ego. It also points out the high probability that we are not alone. Even if life is exceedingly rare in the universe and only takes hold on 1/1000th of 1% of worlds, there are still trillions of planets that harbor life.