The Sky - Planets, Stars & Galaxies

The Era of the Stars - and Their Offspring - Us

Fiat Lux = Let There Be Light

We now live with our daytimes bathed in energy, starlight from our star - the Sun. Stars began to exist over 13 billion years ago, a few hundred million years after the Big Bang? Our sun is about 4.5 billion years old - middle age for a star this size. Below it is shown throwing off a CME - Coronal Mass Ejection - that would fry us if the Earth did not have a strong magnetic field and atmosphere.  Lke all stars, it will burn out. One day all stars will be burned out and matter too spread out to make any more stars - leading to  a dark and cold universe. 


Click for larger image in another window.:

How did our Sun come to be? Well, there are regions were matter gathers - into clumps, then disks, then compresses until the nuclear furnace in the center ignites - making a star. Here is an active star forming region near us [about 1300 light years away] in our Milky Way Galaxy. It is the famous Orion Nebula, M42, that you can see in Orion’s sword, hanging from his belt in the sky - a fuzzy spot to your eye but magnificient in a telescope . 


Click for full size view in another window.:

Your eyes can see a few thousand stars. But your eye’s pupil can only open up to about 7mm or ¼ inch. Our biggest telescopes now are about 10 meters or 30 feet in diameter.

Next, Here is our nearest big neighbor galaxy, M31 - the Andromeda Galaxy - about two million light years away. You can barely see it as a fuzzy spot with the human eye. It is similar to our own Milky Way, hundreds of billions of stars. It is headed this way.

andromeda gendler big

Andromeda Galaxy - M31. Click for larger image in a new window.

Near where I am writing this in New Mexico,  some of my friends work at Apache Point Observatory, where the SDSS - Sloan DIgital Sky Survey is making a computerized map of the whole sky. Here is a video showing about 400,000 galaxies of the estimated hundreds of billions of galaxies in the known universe.

Here are about 400,000 galaxies of the trillion we can see. This video is worth your time, because this is not an artist’s impression but real data.  Remember, these are not stars, but galaxies - each containing hundreds of billions of stars like our Sun. So sit back, go full screen and enjoy.

If that’s not enough, Now let’s try to look at the really BIG PICTURE - the whole universe, or at least our known universe as of 2014. Here is an overview far above and beyond stars, galaxies, clusters of galaxies, even superclusters of galaxies - to webs made of superclusters of galaxies - once again from work at the SDSS - Sloan Digital Sky Survey and by other people as well:
AN IMPORTANT NOTE: The bright spots here are not stars. They are not even galaxies. They are clusters and superclusters of galaxies. The scale of distance here is not miles, but megaparsecs - Mpc = a million parsecs. A parsec is the distance at which the orbit of the  Earth makes an angle of one arcsecond = equal to about 3.26 light-years (31 trillion kilometres or 19 trillion miles) The speed of motion here is megaparsecs per hour = Mpc/h, much faster than the speed of light.

The BIg Picture - even our galaxies are small dots in the web of the universe,
now estimated to be at least 100+ billion light years across.

Finally, another overview - over all we know:


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© Gareth Harris 2016       --------        Contact email:        --------         see also: