Northern Sky Talk podcast

Posted 2008 May 04 @ 12:48 - filed under Astronomy.

Episode 2 of Karol's Northern Sky Talk astronomy podcast is available for your listening pleasure. Karol talks about viewing exotic constellations, the visibility of Saturn, and zooms in on the Moon to find a bridge, a cometary tail, and more. Enjoy!

The stars and planets for May 2008

Posted 2008 April 28 @ 00:15 - filed under Astronomy.

If I ever have to be stranded in space and time, then I’d like it to be on top of Stellenbosch Mountain in the middle of May at eight o’clock the evening. I will also take a towel with me.

May evenings are surely the most impressive. By 19:00 its getting nice and dark and, an hour later, when the Sun is well gone, the serious fun begins.

Two supergiant stars anchor the Milky Way on opposite horizons, like map pins holding down a flapping gossamer cloth. In the west, its Betelgeuse, while in the east, its Antares.

Just above the sunset horizon the bright stars of Orion decorate the night sky, his three-star girdle erect. To the right is the orangey-red Betelgeuse, 600 times larger than our Sun. In the direction the girdle is pointing lies Sirius, brightest star, almost twice the size of the Sun but 20 times younger.

Just above the eastern horizon is the curved outline of Scorpius. The orange-red supergiant Antares is the alpha-star hereabouts. And with right: its 700 times larger than the Sun.

This is the only time of the year you can see these two prominent constellations together in the sky and at opposites; according to Greek legend the two are arch-rivals and stay as far away as possible from each other.

Between these two stretches the Milky Way, the galaxy in which we live and of which our Sun is one amongst 200 billion. Far from city lights, the Milky Way, accompanied by the Magellanic Clouds, is clearly visible.

High up in the south, along the Milky Way, is Crux and the Pointers. In the southwest, between Crux and Sirius, is the bright star Canopus. Draw a line from Sirius to Canopus and now extend it the same distance: you’ve arrived at celestial south.

Now turn to the north. High up is another prominent star, Regulus, in Leo. This year Leo sports a brighter companion: the ringed planet Saturn. Recently at a star part in Sutherland I was showing Saturn through my telescope. One lady stood and looked, long and silently. I thought she may have fallen asleep. And then it came, the soft whisper: “THIS is why I came to Sutherland.”

A ways below and left of Saturn is the orangey Mars; both planets can be seen in the evening sky during May. Draw a line from Mars to Sirius: midway is the bright star Procyon, the main star of the Smaller Dog. Together with Sirius and Betelgeuse it forms the Winter Triangle – a northern hemisphere designation, of course.

Keep an eye on Mars during the third week of May; get out binoculars or a telescope if you have one. The Red Planet is moving in the direction of the pretty open cluster Praesepe (The Beehive, Manger, M44). This cluster can be seen on a dark evening with the naked eye, but with the bright Moon in the vicinity, you’ll need some optical aid. On May 21 the planet is on the outskirts of the stellar grouping, but for the next two evenings it shines amongst the dim stars of the cluster. Sweet. According to my calculations, the next such conjunction is only in November 2009.

Two planets that can usually be counted on to shine brilliantly – Venus and Mercury – are both too near the Sun this month to be readily seen.

The ace-planet, Jupiter, is already above the eastern horizon around 22:00 at night, below the stars of Scorpius and Sagittarius. Jupiter is the brightest “star” in the sky – compare it to Sirius setting in the west as Jupiter rises. The giant planet is also the last “star” visible in the morning sky, high overhead, as the Sun drowns out the night.

The Moon (New on the 5th) returns to the evening sky on Wednesday May 7, very low in the northwest. Look for it as soon as dusk falls; binoculars will make it easier to spot. The bright star Aldebaran (together with the V-shaped star cluster the Hyades) lies to the left of the Moon. By Thursday evening the lunar crescent is much easier to spot.

Watch from the 9th to the 12th as the Moon waxes, moving through the northern stars and past Mars and Saturn. This is a good opportunity to study the movement of the Moon. During the course of a day, the Moon will rise somewhere in the east and later set somewhere in the west, just as the Sun and stars do. This motion is because of the Earth’s rotation, and gives us our “day”. At the same time, the Moon is also moving along its orbit around our planet, one such orbit giving us a “month”. On a given evening, thus, the Moon changes its position in the night sky because (a) the Earth is turning, and (b) the Moon is itself moving. The former causes a noticeable change in position, but the later is more subtle. Monday evening the 12th is a good opportunity to watch out for this.

On the 16th and 17th the Moon is near the star Spica in Virgo. The brighter star below-left of Spica is Arcturus in Bootes the Shepherd.

On the 19th, while the Sun still on the way down and the colour is still in the sky, look out for the almost-Full Moon low in the east (it rises at around 17:15 in Cape Town). On the 20th it is Full Moon. On the 21st, the Moon rises shortly after the Sun sets, and will be impressively big and bright low on the horizon (around 18:40 for Cape Town). The 23rd and 24th finds the Moon near Jupiter, visible all night long until daybreak.

A special event on the 20th/21st should be well worth watching. On Sunday evening, around 19:30, the bright Moon lies a short way above sigma Scorpii. Its moving in the direction of Antares, and by 22:00 it has completed half the journey. Just after midnight, the Moon will occult Antares. The occultation will only be visible from southern Africa, parts of Madagascar, and eastern South America. Seen from Cape Town, Antares disappears begin the bright lunar edge at 00:32:17, and reappears at 02:07:14. Times for other centres are different.

In case it’s cloudy that night, hold thumbs that its good weather on 2008 August 10, when star and Moon do a repeat-performance.

Happy star gazing!

Karoo Fossil Tour 2008

Posted 2008 March 27 @ 00:35 - filed under Stuff.

My head is buzzing with Ecca, dinocephalian, dicynodont, Drie Gots, and much more.

Creationist rubbish: read all about it

Posted 2008 March 14 @ 22:54 - filed under Bullshit.

On March 05, Dr D. J. Batten (B.Sc., Hons., Ph.D.), who is affiliated with Creation Ministeries International, came to spew nonsense on the campus of the University of Stellenbosch. He was introduced by Mr Sias le Roux, of the fundamentalist Christian organization Shofar.

Here's my transcript of Dr Batten's (B.Sc., Hons., Ph.D.) talk. Your comments will be appreciated. When I get back from fossil hunting, I'll make work of them.

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