Have you ever used the expression “That’s astronomical to describe something of really large proportion or an extremely large number? Well there is good reason why that expression came into common parlance.
The immense proportions of our Universe is one of the aspects of amateur astronomy that so intrigues people as they begin to gaze out into the abyss of space. It brings a unique concept of relative proportion to the things around us. Our world can appear to be an extremely vast place (try crossing the Atlantic on a small boat), but in the context of our Universe it practically disappears into insignificance. With one exception; the carbon based life that abounds here is a remarkable phenomenon on the scale of being statistically impossible even in the face of a Universe with an estimated 5 billion trillion stars and some 13 – 16 Billion light years in size, which also happens to define it's age (more on this in a bit).
A host of magnificent and bizarre objects that are at once beautiful and hostile surround us. Continual cataclysmic events send shock waves through space that make earth’s largest quakes and volcanic eruptions seem tame. The night sky reveals a beauty of design that both mirrors elements of nature here on earth and at the same time is as strange and bizarre as anything ever imagined by the writers who transform these worlds into wild fiction.
So, if you are new to astronomy, here are a few fascinating facts that will increase your appreciation of the myriad points of light you can see in a dark night sky with your naked eye. Facts that can transform faint fuzzy objects viewed through a pair of binoculars or a small telescope into mystical wonders. Facts that when pondered, can dwindle your overwhelming challenges into molehills of serenity. Facts that can also give new depth of meaning and appreciation to the objects imaged on this website.
Our Solar System
Distance and Light
The Milky Way Galaxy and our Neighbors
You can see our nearest galactic neighbor (the Andromeda Galaxy) with the unaided eye under dark skies. It is 2.2 million light-years distant and contains about 300 billion stars.
How Fast is Fast?
In addition to this, the Universe is expanding, so our galaxy is moving away from most other objects. This is a very complex number as it is based on some very heavy theory regarding the fundamentals of the formation and age of our Universe, and is still being debated by the most brilliant minds of our day. However the general consensus is; between 57 & 78 kilometers per second per megaparsec (never mind about this now). We begin to enter Wonderland on this one, but the further out, the faster galaxies are moving away from us at a rate of something like 162,000 miles per hour for every 3.26 million light-years further out we look.
All in all, that’s pretty darn fast, so what is a few miles per hour? nest time you are stuck in a traffic jam, sit back and relax. Remember you are still whizzing around the Universe at “Warp” speed.
The (average) distance from the Earth to the Sun is approximately 92.8 million miles, which is also known as One AU or Astronomical Unit.
By comparison our moon is a mere 238,330 miles away (384,400 kms)
Our Sun is 109 times the size of the Earth and contains 98.9 percent of the mass of the whole solar system. Its center is a huge thermonuclear furnace stoked by hydrogen fusion creating temperatures in excess of 16,000 degrees F at the surface, and 2 million degrees in the upper photosphere.
Our Sun is smaller than 99 percent of the stars visible to the unaided eye.
Light travels (in empty space) at a speed of 185,871 miles (299,792 km) per second, so it takes about 8 minutes and 19 seconds for light from the sun to reach Earth.
Space is so vast that different units of measure need to be adopted to cope with them.
A light year is a measure of distance, not time. It represents the distance that light travels in one year, which is the equivalent of 5.83 trillion miles (9.5 trillion kms) For more dramatic effect = 5,831,571,200,000,000,000 miles.
The most distant probe we have sent out to explore space has reached a distance of some 6.54 billion miles, which equates to only about 20 light hours.
The nearest star Proxima Centauri is 4.225 light-years from Earth.
These are big numbers, so to get an idea how big, consider this: A billion sheets of average thickness paper would make a stack 10 times higher than Mt Everest. A stack of a trillion sheets of paper would reach ¼ of the way to the moon. Put another way, a trillion seconds is about 300 centuries
Our Milky Way Galaxy is 90,000 light-years in diameter and 10,000 light-years thick at the central bulge and has at least 200 billion stars. Our Sun is just one of these medium sized stars.
Our sun lies approximately 30,000 light years from the center of our galaxy
Estimates are that there are at least 5 billion trillion stars in the Universe.
Under very remote dark skies, only about 5,000 stars a visible to the naked eye.
If you feel like you are slowing down some in your old age, consider this. As you sit in your lazy boy, munching chips, you are only moving a minute proportion slower that the fastest human on the face of the earth. As our friend Albert Einstein would say; “It’s all relative”.
You are spinning around the Earth at an approximate rate of 1,000 miles per hour. (We will keep this simple). The exact rate would be determined by the circumference of the earth at your particular latitude divided by 23 hours, 56 minutes. If you like math, then your circumference (c) = 2 pi r cos (x) where r= radius of earth (6,378 km) and x = your latitude
The Earth is rotating around the Sun at an approximate rate of 64,000 miles per hour.
The Sun is rotating around the center of our galaxy (The Milky Way) at approximately 170 miles
(274 km) per second
Fascinating Astronomical Facts