Category Archives: Astronomy 101

One of my main goals is to try and share a bit of knowledge and understanding about the incredible universe. I have been steadily writing and posting various articles to explain and educate the masses (that’s you, dear reader!) a bit more about some of the science behind the hobby. An urban astronomer might never see most of the things we talk about here, but it’s still good to know about them.

What is space junk?

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Space junk is any manmade object orbiting Earth that nobody owns, or that nobody controls.  It’s litter, basically, and consists of everything from used-up rocket boosters and dead satellites, to nuts and bolts dropped by careless astronauts.  Even though space is very big, it’s still becoming enough of a problem that the International Space Station has had to dodge many objects since it was first built, and at least one privately owned communication satellite has been destroyed in a collision … Continue reading →

What causes a halo around the Moon or Sun?

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A few days ago, a newspaper received a photograph of a Lunar Halo from one of their readers and asked me to explain what was going on.  You can click on the above link to read my answer, but it was by necessity rather short, and incomplete.  So what’s the full story? What we see in the image to the right is a full moon, surrounded by a colourful halo, with the constellation Scorpius faintly visible along the top border. … Continue reading →

What is an exoplanet?

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An exoplanet is a planet which is not a part of our Solar System.  Although nobody knew for sure if they even existed 20 years ago, they are now being discovered at an incredible speed – more than one every single day.  Because even the nearest stars are so far away, they are incredibly hard to see, which is why so far even the smallest yet discovered are much much larger than the Earth.     Comments?  Questions?  Why not … Continue reading →

How old is the Earth?

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The Earth is about 4.5 billion years old.  This age is deduced by radiometric dating (Carbon-14 dating is one form of radiometric dating, suitable for archaeogical timespans.  Other isotopes are needed to measure really long periods of time) — the oldest rocks anybody has found on Earth are about four and a half billion years old.  Extreme ages of the planet are backed up by the times required for geological features to form, life to evolve, the age of the … Continue reading →