Since watching some episodes of “The Universe” (History Channel) a year or two ago, I’ve wanted to know what I was seeing when I looked up at the stars. I wanted to be able to recognize the constellations, and I wanted to be able to marvel at the fact that a certain star that I was looking at was a certain size, or a certain distance from the earth.
So last month I decided to start learning astronomy. Before I explain how I got started & how you can too if you have the urge, here are a few astronomy facts to whet your appetite. (If all you want is to start doing astronomy, scroll down to the heading “Tips To Get Started”)
Our Star, The Sun
The sun looks roughly the same size as the moon from our perspective. But whereas the moon is much smaller than the earth, the sun is so big that over 1 million earths could fit inside of it.
The sun is made of mostly hydrogen and helium. The hydrogen atoms are flying around so fast in sun’s core that when two hydrogen atoms smash into each other, they fuse and become one helium atom. Every second, the sun fuses about 600 million tons of hydrogen into 595 million tons of helium. In the process, it gives off a lot of energy.
Every second the sun gives off about as much energy as a billion 1-megaton hydrogen bombs going off. The Hoover Dam has a maximum capacity of 2,080 megawatts of power. The sun generates 386 billion billion megawatts of power. (the 2nd “billion” is not a typo)
After the sun fuses all of its available hydrogen into helium (billions of years from now) it will gradually cool off and fade away.
Light Speed & The Size Of The Milky Way
As you probably know, the Milky Way is our galaxy. It is a huge disc of about 200-400 billion stars including our sun. Here’s one way to put the Milky Way’s size in perspective…
Imagine getting into your car and driving to another city that is 300 kilometers away. Driving in a straight line at 100 km/h (about 60 mph), it would take you 3 hours to get there.
How long would it take light (the fastest thing in the universe) to get from your city to the other city? In 1 second, light would have travelled between the two cities 1,000 times!
And how long would it take light, traveling at that unimaginably fast speed, to get from one edge of our Milky Way galaxy to the other edge? One hundred thousand years.
And yet, despite its amazing size, the Milky way is a mere pin prick on the scale of the universe; it is just one of hundreds of billions of galaxies.
Where We Came From
Many stars that are more massive than our sun start by fusing hydrogen into helium like our sun does. But because of their size & hotter temperate they’ll then start fusing the helium in carbon, carbon into oxygen & nitrogen, and so on, fusing lighter elements into heavier elements until the core of the star is a huge ball of iron.
It is inside of stars that all these elements of the universe get made. Once massive stars run out of elements to fuse together, they collapse in on themselves and then rebound outwards in a massive explosion called a supernova.
Astrophysicist Alex Filipenko says, “The elements in your body, not just generically, but specifically, the elements in your body heavier than hydrogen and helium came from long-dead stars. The calcium in your bones, the oxygen that you breath, the iron in your red blood cells, the carbon in most of your cells, all those things were created in stars through nuclear reactions, and then ejected by supernovae. And the heaviest elements, iron and above, were produced by the explosions themselves; by the supernovae.”
As Carl Sagan put it, we are “stardust”, literally. And Neil Degrass Tyson points out that “We are in the universe, and the universe is in us.”
Looking Back In Time
If you want to look into your own past, you might open up an old photo album.
To look into the very ancient past, you might start digging into the ground, finding old human civilizations, bones of the ancestors from whom we evolved, and dinosaur bones.
But to look farther into the past than we’ll ever see digging into the earth, we must look out into space.
The farther away a star is, the farther back in time you’re looking when you see it. That’s because it takes time for the light from the stars to reach your eyes. When astronomers see a star millions of light years away go supernova, they are watching an explosion, right now, that happened millions of years ago.
It’s hard to see things millions of light years away with your naked eyes, but you can easily look up and see thousands of years into the past. Some of the stars that you can see with your naked eyes might have exploded hundreds or thousands of years ago and may no longer exist, but the light from those explosions hasn’t reached the earth yet. So to us, the stars still look just like they did hundreds (or thousands) of years ago.
Rather than seeing some dead bones of dinosaurs, stargazing is like looking into the past and seeing living dinosaurs running around. You’re seeing the universe EXACTLY as it was at that time, rather than some leftover remains.
How far back can astronomers see? The universe is 13.7 billion years old, and the most powerful telescopes can see all the way back to just 300,000 years after the big bang. That means that if the timeline of the universe was 1 kilometer long, they can see all the way back to about 2 centimeters from the beginning.
Tips To Get Started With Astronomy
Below are the things that I did to start learning astronomy, and I found that they were effective. I’m by no means an expert after a month of stargazing, but if I was going to go back in time and learn astronomy again, I don’t think change anything.
Read These Articles
I started my month by reading through the list of “Stargazing Basics” articles on SkyAndTelescope.com. Those articles are super helpful and easy to understand. Just read them. Or at least skim them.
Find Local Astronomy Groups
There are amateur astronomer groups in my city that put on various events. Thanks for those groups I was able to attend a few talks on astronomy as well as a couple of “star parties” where members bring their telescopes out at night and let people look through them.
I found that everyone was very helpful at all these events, and some of their telescopes were quite impressive (one was about 10 feet tall)!
Memorize The Constellations
I spent some time each day for a week or two trying to memorize the constellations. I’d look at a star chart, flip it over, and then draw as many dots (stars) as I could remember on a blank sheet of paper. By repeating that process over & over I was eventually able to draw many of the significant constellations in my night sky at this time of year.
I first went out and looked at the stars after about a week of copying the chart. It was satisfying to look up & recognize in the sky what I’d been drawing on paper.
And it’s nice to look up and know which stars are which without needing a chart right there with you. I certainly don’t know them all, but have got the broad patterns down.
Watch “The Universe”
I must say that although some of the episodes are packed with well-presented mind-blowing information, many of them are very slow and repetitive. The difference in quality from one episode to the next made it hard to believe that the same people were creating them. I do recommend “The Universe“, but expect to be disappointed by many of the episodes.
Get A Laser
The stars look like a big mess of dots, and it can be painfully difficult to point out one particular star or constellation to someone. A laser makes the job super easy – you just point and say “that star”. (And I do suggest looking at the stars with other people – as Christopher McCandless wrote: “Happiness only real when shared.”)
Lasers used for astronomy are green, because our eyes can see green light easily. You won’t see the beam from red laser pointers. You can buy green lasers online or at astronomy / birdwatching stores. (mine is 10 mW and is more than bright enough)
Warning: Lasers are dangerous. Don’t point them towards eyes, aircraft, or reflective surfaces.
Use Your Naked Eyes (Don’t Buy A Telescope Yet)
I don’t own a telescope. There’s plenty to see, learn, and be amazed by with just your naked eyes, or binoculars.
If you do have a chance to look through a telescope, prepare to be underwhelmed. One of the coolest things you might be able to see is Saturn – but even Saturn is just a small white circle with a small white ring around it – it won’t look anything like the detailed color photos that you’ve seen. Most other objects that you’ll see through a telescope aren’t much more than a little dot, or a little fuzzy blob in the sky.
What makes looking at a tiny faint fuzzy dot amazing is knowing that that dot is not a star, but a distant cluster of 100s of thousands of stars, knowing that each of those stars on average could contain a million Earths, and wondering whether somewhere in that enormous pinprick of light there might be another life form looking back.