From a Flammarion woodcut, unknown artist.
From a Flammarion woodcut, unknown artist.

I decided that instead of blogging on just one topic in astronomy, I’d blog about ten of them! Here are some of the astronomy fun facts from my archive that struck my fancy today, randomly chosen and in no particular order:

1. In the city we can see maybe a few dozen stars on a “dark” night—still, there are about 2000 stars overhead that are within our eye’s ability to see, if only the skies were darker! The total number of individual stars perceptible by the human eye, in all directions in space, is around 6000, give or take depending on how good your eyesight and night vision are.

2. In terms of size, the Earth is over 6 million times larger than a human being; compared to a typical atom, a human is over 20 billion times larger! Our personal scale in the universe is a lot closer that of even the vast Earth we live on than to the atoms that make us!

3. The largest known star, the red supergiant NML Cygni, is approximately 1650 times the diameter of our sun, or over 1.4 billion miles across! Placed where our sun is, this star would swallow up all the planets closer to the sun than Saturn—and Saturn itself would practically skim the star’s surface!

4. In about 5 billion years a day on Earth will be 48 hours long and the sun will start to run out of fuel. So, yes, we live on a planet orbiting a star, both of which are slowly winding down.

5. Television transmissions from the earliest TV broadcasts have traveled over 70 light years into space and have passed through over 500 star systems, many with known planets. I Love Lucy original broadcasts are at this moment reaching other planets!

6. There is roughly the same number of stars in the universe as water molecules in a drop of water. This kind of fact always turns my attention away from how big the universe is to how ridiculously small its constituent parts are.

7. The old Greek word for “comet” is “disaster”. It means literally “bad star.” Many cultures regarded the appearance of a comet in the skies a bad omen or harbinger of doom. Have you seen a disaster lately?

8. The moon may be 400 times smaller than the sun, but since it’s 400 times closer to us they appear exactly the same size! What a coincidence. Since the moon was once much closer to Earth, and will in the future get much farther away (at a rate of mere inches per year), it is a bit of a coincidence, really. But, of course, it was bound to pass through this state at some point, and the only real coincidence is that we are alive at present to remark on it.

9. The most distant object in the Universe perceivable to the unaided human eye is the Andromeda Galaxy, about 2.5 million light years away! That’s 15 billion billion miles! Everything else we can see without a telescope is a lot closer to us!

10. Imagine taking the entire Earth and everything in it and crushing it to a mere point in space, infinitely smaller than a grain of sand. This idea may be beyond imagination, but it’s not beyond nature. Black holes are points in space where the mass of entire stars, and even millions or billions of stars, has collapsed. Kind of makes one re-think what solid matter actually means.

And the list goes on. What a privilege to exist in a reality where such mind-boggling facts absolutely abound!

Ten Random Astro-Facts to Entertain and Boggle 11 June,2013Ben Burress

  • Dan L

    So, “I Love Lucy” is now passing other planets. Any wonder why the intelligent life out there isn’t calling us?

    • At the speed of light their reply would take as long as it took for Lucy to get to them.

  • Mallet Head

    If you stand in your backyard and shine a flashlight beam on the darker part of the moon why can’t the light be seen there? The beam spreads. Why would anyone think radio/tv waves wouldn’t? After two or three lys, the beam will be too diffuse to detect without a solar system sized receiver.

    • Ben Burress

      As for being able to detect radio signals over many light years and why would anyone expect to be able to detect them, you might direct this question to someone at SETI (Search for Extraterrestrial Intelligence), who are using an enormous array of radio telescopes (the Allen Telescope Array) to listen for the radio signals from other hypothetical civilizations. You certainly can’t see the reflected light from your flashlight bouncing off the Moon; the visible light returning to you is far too weak for the human eye to detect–the human eye isn’t sensitive enough. However, some of the light DOES in fact bounce back and reach your eye. As for radio waves, not only do HAM radio operators send radio signals toward the Moon, they detect the signal that bounces off of small retroreflectors left behind by the Apollo astronauts. And with large radio telescope dishes radio astronomers are able to detect extremely faint signals from distant regions of space. It’s totally feasible, given the right radio receiver gear, to detect the sparse-but-present I Love Lucy signals even after it has traveled light years.

  • Skeptical

    There is no way the earth is only six million times the size of a person. I mean, there are seven BILLION people on the earth. Are you suggesting that all of us combined are more than a thousand times larger than the earth??

    • Mallet Head

      haha good point, I should have caught that 🙂 IDK maybe they mean it would take 6M people, head to toe, to circle the globe at the equator, which is, as you point out, not at all the same as saying 6M x’s the size of a person. Actually it would take closer to 7M given an average height of 6 feet … but why quibble the number is so far off it doesn’t matter … nice catch

      • Ben Burress

        Yes, I did mean height of a person when I said size. I find that when I mean volume or mass of a person when I say size, most people automatically assume that height is what is being talked about. And while I was also using a smaller value for the average height of an adult human (which is less than 6 feet, actually, and which gave me a factor of over 7.5 million), I tend to round down the estimates to try to avoid hyperbolae, hence my answer of “OVER 6 million times larger”.

    • Arthurjg

      I read somewhere all the people on earth could fit in Duval county fl

  • Denver Jay

    yeah this whole post is suspect. The number of stars in the universe is unknown and unknowable, but I bet it is much higher than the amount of molecules in a drop of water. and I also doubt that only 2000 stars are visible with the naked eye. Who edited this? maybe the headline should be “10 random facts I just made up”

    • Ben Burress

      The number of stars in the observable universe is an estimate of course. It is based on the estimate of the number of galaxies, which currently is placed between 50 billion and 100 billion. Using the lower-end number in that range, 50 billion, and assuming a modest average number of stars per galaxy of 10 billion (the Milky Way itself, a moderate sized galaxy, contains an estimated 200 billion), the product is 500 billion billion, or 5 times ten to the 20th power. There are approximately 7 times ten to the 24th power water molecules in an 8 ounce glass of water–so even if a single drop of water were assumed to be a mere 50th of a cc in volume, you’d still get over 6 times ten the the 20th power water molecules in that drop. 500 billion billion stars in the universe versus 600 billion billion water molecules in a drop of water.

  • Bob K

    Skeptics, these are amazing true facts! It is a happy coincidence that the sun and moon appear to be the same size in the sky, since the moon gives us light at night when it is dark, and the sun only shines in the daytime when it is light anyway.

  • Yohoyo

    Yo yo yo!


Ben Burress

Benjamin Burress has been a staff astronomer at Chabot Space & Science Center since July 1999. He graduated from Sonoma State University in 1985 with a bachelor’s degree in physics (and minor in astronomy), after which he signed on for a two-year stint in the Peace Corps, where he taught physics and mathematics in the African nation of Cameroon. From 1989-96 he served on the crew of NASA’s Kuiper Airborne Observatory at Ames Research Center in Mountain View, CA. From 1996-99, he was Head Observer at the Naval Prototype Optical Interferometer program at Lowell Observatory in Flagstaff, AZ.

Read his previous contributions to QUEST, a project dedicated to exploring the Science of Sustainability.

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