Archive for new zealand

Why are there 24 hours in a day?

Posted in News & Events, Tips & Hints with tags , , , on June 6, 2011 by astronomymike

To be honest, there are some things in this life that I have never given a second thought to…and this question was one of those things. At least, that was until our small astronomy group had the pleasure of hosting Wellington-based astronomer Frank Andrews at one of our monthly meetings!

Human beings are a remarkable species, but we also have an incredible ability to just accept everyday things, without question, just because “they are”. For me, having 24 hours in a day definitely fell into that category. It wasn’t until our esteemed presenter asked the question, “why?”, that I had to admit I hadn’t the slightest clue! Do you? Doesn’t 24 seem rather arbitrary when you think about it?

Well, you’ll have to forgive me if I get some of the finer detail wrong, but in truth I was more interested in the “why” than the “who”. Let’s just say it was in “ancient times”, perhaps the Sumerians or the Babylonians, and in those ages everything was related to “the gods”. The gods were perfect, they lived in the sky (represented by the stars) and passed overhead in an arc every night. So how does one represent the perfection of the gods watching over us during the cycle of day and night? Well, with a perfect circle of course! So, how do we divide up a 360° circle into even pieces? The most obvious is to divide it into half, making 2 x 180° pieces. Dividing each of those in half again gives 4 x 90° pieces, and again 8 x 45° chunks. But if we again try to divide the pieces, we end up with a non-whole (and therefore “imperfect”!) number – 22.5°. It also leaves us with a “clock” that represents an entire day/night cycle of only 8 evenly-divisible pieces – not particularly accurate at describing a time of day or night.

So, how else can we divide a perfect circle into “even” pieces of smaller size and whole (perfect) numbers? How about thirds? The first division give us 3 x 120° pieces, the second 6 x 60°, the third 12 x 30° and finally, the fourth division will give us 24 x 15° pieces. Nice! A further division will, of course, give us a non-whole and therefore imperfect number, but 24 pieces is a much more accurate way to be able describe a particular time than 8 pieces, don’t you think?

Oh, and one more thing – why do we call a “minute” a minute and a “second” a second? The first comes from the Latin word “minuta”, meaning “small”, and refers to the (first) minute (part) – in other words, it is the first minute part (or division) of the hour. Naturally the “second” refers to the second minute part, achieved by dividing the first minute part into smaller pieces.

I hope you learned something from that…I know I certainly did.

Thanks for reading, and wishing you clear skies!


AstronomyMike has landed!

Posted in Images, News & Events with tags , , , , , , , , on January 6, 2010 by astronomymike

Hi all, and welcome to my Southern Hemisphere astronomy blog.  Please bear with me while I get used to this blogging lark!

Anyway, I thought that I’d give this a go, now that the Christmas and New Year antics are over, so I hope you enjoy it.  The main reason for setting up this blog was so that I could encourage as many of you as possible to take an interest in what many of us take for granted – the night sky.  Feel free to pop over to my About AstronomyMike page to find out how I got involved in astronomy and what equipment I use.

For now, my astronomy equipment limits me to imaging the Moon and planets in our own solar system, but eventually I hope to be able to do some deep sky imaging so you can see some of the incredibly stunning nebulae and galaxies that are out there.  That’s not to say that the Moon and our planets are boring!  Far from it.  In fact, it wasn’t until I started imaging these objects that I realised how much there was to learn about them, and I hope to be able to pass on some of this information with images that I share with you.

Here are a couple of my recent images that won first place and first equal respectively in the RASNZ (Royal Astronomical Society of NZ) Spring 2009 Astrophotography Competitions :-

Craters Catharina, Cyrillus & Theophilus

First Place - Solar System Category

The 3 large craters (top to bottom) are Catharina, Cyrillus and Theophilus.  To the left of the craters is Mare Nectaris (the smooth lava-flooded impact basin).  Not far to the right of Cyrillus was the landing site of Apollo 16.

7.5 Day (First Quarter) Moon

First Equal Place - Favourite Category

This is an image of a 7.5-day (First Quarter) Moon (in other words, 7.5 days after New Moon) taken on November 24, 2009, and is a mosaic of 4 images stitched together to create one large image.

It’s nice to see that Joel Raupe has blogged about a couple of my images too over at Lunar Networks! Thanks Joel.

I look forward to sharing some more images with you soon!

Clear skies! – Mike

AstronomyMike will be here soon!

Posted in Uncategorized with tags , , , , on January 5, 2010 by astronomymike

Greetings Earthlings!  AstronomyMike is preparing to teleport his astronomy blog and will be with you shortly!

In the meantime, feel free to read About AstronomyMike or view some of my Flickr images and videos from the sidebar.