Starry, starry night: Grasping just how vast the universe really is
Special to the Daily
Let’s start off with a photograph of nothing. In 1995, NASA pointed the Hubble Space Telescope to an area above the Big Dipper that was not known to have anything significant in it.
The Hubble Space Telescope is a large, space-based observatory orbiting the Earth. In that year astronomer Robert Williams, who was the director of Hubble, had decided to ignore the people who thought it would be a huge waste of time and money to look at nothing in particular. He went ahead and had the telescope point to nothing. The resulting photo was assembled from 342 stacked and blended images taken over 10 days by the Hubble Wide Field and Planetary Camera 2. That photo changed astronomy forever.
What resulted was a view of the universe that included only one star. All the other spots of light in that image are from hundreds, maybe thousands of galaxies.
What is more amazing is that if you held a pin at arm’s length, the head of the pin would completely cover the field of view seen in the photo. The light from those galaxies started the trip to Earth 800 million years or more in the past. Since then, Hubble has been pointed at more nothing and the results have been the same — thousands and thousands and thousands of galaxies.
It is time to really examine the numbers. Be prepared. This could fry some brain cells.
How many galaxies are there in the observable universe?
Using Hubble that estimate is 50 billion (50,000,000,000) galaxies.
How many stars in a galaxy?
Astronomers estimate there are about 400 thousand million stars in our galaxy, the Milky Way. Some galaxies may have a trillion stars.
How far away are those stars and galaxies? Astronomers use the speed of light as one way to describe how far away things are in space. Light travels at a speed of 186,282 miles per second. A light year is how far light travels in a year, about 6 trillion miles.
How far is the nearest star that is not our sun? Proxima Centauri, in our Milky Way Galaxy, is about 4.3 light years away. (i.e., 4.3 x 6 trillion miles = 25,800,000,000,000 miles!)
The Andromeda Galaxy is approximately 2.5 million light years from Earth. That means that the light that passed through the glass of my telescope left Andromeda 2.5 million years ago.
It is 15 million trillion miles from Earth (15,000,000,000,000,000,000). It is also huge, more than 110,000 light years in diameter and contains more than 1,000,000,000,000 stars. The galaxy is very dim and larger than the full moon in the night sky. You can see some of the Andromeda Galaxy as smudge in the sky with the naked eye under moonless, dark conditions. Binoculars or a telescope make that view better. Andromeda is the most distant object you can see with the naked eye.
I have run out of exclamation points! If your head is not spinning by now, you have not been paying attention. But let’s go one last step to big.
The Kepler Space Telescope has been collecting data for over nine years. It has been looking for exoplanets, planets that orbit distant stars. It has found thousands and the data reveals that there are probably more planets in the universe than there are stars.
Is there some intelligent organism looking back at us?
The Kepler space telescope has run out of fuel and research using that instrument is being discontinued. The James Webb Space Telescope, now due to launch in 2021, is NASA’s newest planet hunter and will be able to “see” even more objects in the universe.
How can you really enjoy the night sky? From most places in the valley, it is pretty dark, and a lot of stars are visible. But you need to get to somewhere really dark to really see something amazing.
During the new moon (for this month, the days around January 20) go to the Wolcott exit, or better yet to the top of Tennessee Pass, at 10,424 ft, on Highway 24. Get away from all the lights. Take your binoculars. Avert your vision from the lights of passing cars.
After about 10 minutes in the dark the number of stars you can see is truly amazing. The Milky Way is a hazy band of stars. Look closely across the sky and you will see a few fuzzy patches or smudges. Those are the galaxies and nebula in the universe.
Cold, cloudless nights are incredible. On a really clear, new moon night, using the naked eye, you could see thousands of objects in the sky and a half dozen galaxies and nebulae. With binoculars there would be many more.
Here are some common deep space objects that amateur astronomers search for.
Andromeda Galaxy and the moon
To illustrate the size of Andromeda, I created a composite of the moon and Andromeda, taken on the same night, as they are visible with a telescope in the night sky. Both images were shot with the same telescope and camera and neither was resized or cropped.
The moon is a mere 238,900 miless from Earth. Andromeda is in the far, really far distance at 15,000,000,000,000,000,000 miles from Earth. It has an incredible diameter of 220,000 light years and fills a huge area of the sky, but individual stars are so dim that it cannot be seen in its entirety with the naked eye.
The Running Man Nebula and the Orion Nebula
The Running Man Nebula on the left and the Orion Nebula on the right are diffuse nebula located in the Milky Way about 1,344 light years from Earth. They are located about midway down the line of stars that form Orion’s Sword and are among the brightest nebulae visible to the naked eye in the night sky. The Orion constellation is moving into the night sky over the next few months.
The Horsehead Nebula
One of the most well know nebulas is the Horsehead Nebula which is about 1,500 light years from Earth. It is also located in the constellation of Orion. This nebula is located just below the left most star of Orion’s Belt, and is part of the much larger Orion Molecular Cloud Complex The horsehead is actually a dust cloud that is illuminated from behind by a larger cloud of charged gas that appears red. The Flame Nebula is on the left and is 1,350 light years from Earth.
Caldwell 10 is an open star cluster in the constellation Cassiopeia. It has an estimated 400 stars and is 6,850 light years away. Star clusters and globular clusters are similar, however globular star clusters are more symmetrical in shape, and stars tend to move in an orbit above and below the galactic disk of the Milky Way. Star clusters are found inside the disk of the Milky Way. This area of the sky can be covered with the tip of your little finger.
“We live on a hunk of rock and metal that circles a humdrum star that is one of 400 billion other stars that make up the Milky Way Galaxy, which is one of billions of other galaxies which make up a universe which may be one of a very large number, perhaps an infinite number, of other universes. That is a perspective on human life and our culture that is well worth pondering.” — Carl Sagan.
Rick Spitzer is an acclaimed wildlife photographer who lives in Wildridge. He has been dabbling in astrophotography in 2020 as COVID-19 has kept him closer to home.