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.

Lyrids

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The Lyrid meteor shower is one of the better known highlights of the meteor-watching calendar.  It usually peaks around three weeks into April, and while it doesn’t produce many meteors (5-10 per hour, although some years have unexpectedly surged to more than 100 per hour), they’re reasonably bright and hard to miss, with the occasional fireballs that cast shadows for a few fractions of a second.   As the name suggests, Lyrids have their radiant in the northern constellation Lyra … Continue reading →

What is an equinox?

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An equinox is a point in the Earth’s orbit when day and night are both exactly the same length.  There are two equinoxes (or equinoctes if you want to be excessively correct) each year, but they also mark the change of the seasons between warm and cold.  The Earth’s axis is tilted, so that for half of each year, one hemisphere is tilted towards the Sun, so that it gets more heat and light from the Sun that the other. … Continue reading →

What does Jupiter weigh?

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Jupiter has a mass of about 1.9 x 1027kg – 1900 trillion Trillion kilogrammes.  That’s more than double all the other planets, asteroids, comets and dust of the entire Solar System put together.  Jupiter is BIG, yet still manages to not weigh anything at all.  How?  Because it is in orbit around the Sun, just like an astronaut orbits the Earth, and so experiences zero gravity.  That’s not to say there is no gravity around Jupiter – it has plenty gravity … Continue reading →

What does Mars weigh?

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Mars does not have a weight, but does have a mass of about 6.4 x 1023 kilograms, which is a little more than a tenth that of Earth.  When astronauts or spacecraft orbit the Earth, we describe them as being weightless, because they are in freefall.  They are not resisting gravity (the way your body does when you stand on the ground) so “Weight” becomes a totally meaningless concept when you’re in space.    Written by Allen Versfeld Comments?  Questions? … Continue reading →

What does Venus weigh?

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Don’t you know you’re never supposed to ask a lady her weight?  I can probably get away with telling her mass, though, which is about 4.87×1024 kilograms (Or to write it in tonnes: 4870 million million million tonnes).  That means that Venus has about 82% of the Earth’s mass.  Of course, mass and weight are two totally different things (even though the units we normally use for them happen to match up on the surface of the Earth).  Like all … Continue reading →