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 the Cosmic Microwave Background?

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The Cosmic Microwave Background (CMB) is a steady low-level microwave radiation that glows throughout the entire universe.  It is the last echo of the heat of creation.  For the first few hundred thousand years or so after the Big Bang, space was crammed full of a plasma of subatomic particles, so hot that they could not combine into atoms.  But as it all expanded, the temperature dropped until suddenly it was cool enough that electrons could pair up with protons … Continue reading →

How old is the universe?

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13.82 billion years old.  This precise figure is thanks to the data collected by the Planck spacecraft, which was announced in March 2013.  The previous best estimate was 13.73 billion years (give or take less than 1%), which came from the  WMAP satellite.   Both missions mapped out the Cosmic Microwave Background in unprecedented detail, allowing scientists to calculate the Hubble Constant.  The Hubble Constant is the key value in the formula to calculate the age of the universe, which … Continue reading →

Mercury

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Mercury is one of The five classical planets and an easy naked eye object.  The planets stood out from the other stars to our ancestors because of the way they all moved in regular patterns against the night sky, but Mercury was unique in its rapid motion and the way it never strayed far from the sun.  If the planets were to be named for gods, then it was only natural that the flighty mercurial one should be their messenger. … Continue reading →

What is a dwarf planet?

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A dwarf planet a member of the Solar System that doesn’t quite meet the definition of a planet.  It is defined as an object that is in orbit around the Sun, that has enough mass for its self-gravity to squeeze it into a mostly spherical shape, that has not cleared the neighbourhood around its orbit, and that is not a satellite.  The most famous dwarf planet is Pluto, but others include Haumea, Makemake, Eris and Ceres (which is also the … Continue reading →

What is an occultation?

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An occultation is whenever one object in the sky passes in front of another and temporarily obscures our view of that second object.  As enormous as space is, different objects do still sometimes line up and when this happens we say that the nearer object has “occulted” the further one.  Most occultations are caused by the Moon – it’s quite large and moves quite fast against the stellar background, so it occults any number of stars every day.  Less often, … Continue reading →