Search found 336 matches

by KendalAstronomer
Wed Dec 12, 2007 8:49 pm
Forum: Absolute beginners
Topic: Altitude confusion
Replies: 7
Views: 2479

If you consider yourself surounded by an enormous sphere, its equator is zero degrees altitude and right above you, your zenith is at ninety degrees altitude. If you draw a line from the centre of the sphere to any object, the angle that line makes to the plane of the equator (your horizon, ie the g...
by KendalAstronomer
Wed Dec 05, 2007 10:10 pm
Forum: Absolute beginners
Topic: Just wondering about what my little scope can see
Replies: 3
Views: 1473

The Pleiades is a wonderful star cluster I used to spend hours looking at in a far lower power scope, so they should be a good sight. The planets should mostly be good targets (rings of Saturn, though not much detail on the planet, should be visible along with moons, maybe some detail on Jupiter, ce...
by KendalAstronomer
Mon Nov 26, 2007 9:16 pm
Forum: Astrophysics
Topic: Photons do not exist.
Replies: 20
Views: 9128

About the quantum nature of light, look up the ideas of squeezed photons, Bose-Einstein condensates and quantum noise. As a theoretical/mathematical physicist I am much more happy discussing photons in the language of quantum field theory as opposed to talking about experiments. My head hurts even ...
by KendalAstronomer
Mon Nov 26, 2007 9:10 pm
Forum: Astrophysics
Topic: What gives M27 it's distinctive Dumbell shape?
Replies: 4
Views: 3330

Many outbursts occur with two enormous streams at either pole. These streams would be areas of greater pressure than the standard shells of escaping material happening at the equator. This would blow away the hydrogen, leaving the denser, slower oxygen stream visible in the jets. The shell of materi...
by KendalAstronomer
Wed Nov 21, 2007 11:51 pm
Forum: General chat
Topic: Wall Calendar
Replies: 22
Views: 5787

A chat with the Occultations sectionof the SPA may be helpful. Transits of pinprick sized objects tend to test the planetarium programs a little.
by KendalAstronomer
Fri Nov 16, 2007 11:21 pm
Forum: General chat
Topic: Wall Calendar
Replies: 22
Views: 5787

Little moon phase icon in the upper left of the day, maybe a meteor icon on the right for the standard storms, plus any particular other expected things (brighter comets, auroral activity peaks, eclipses, transits, occultations), just as quick reminders. Then lots of nice pics of the good things (se...
by KendalAstronomer
Wed Nov 14, 2007 10:32 pm
Forum: General chat
Topic: Very detailed star map?
Replies: 2
Views: 1020

The very ancient star names tend to be limited by what people could see in the sky, whereas modern skymaps have to take into account the myriad dimmer stars visible with modern telescopes, which should make many of them more detailed than would be required.
by KendalAstronomer
Wed Nov 14, 2007 10:29 pm
Forum: Absolute beginners
Topic: Measuring the mass of Jupiter: Io not quite right :roll:
Replies: 9
Views: 2654

I vaguely recall doing something slightly similar while I was doing A-levels, I remember doing this as well (Distance Learning), only I had to observe the moons visually over a period of around a month. My values for Jupiter's mass varied quite a bit depending on which moon was used, I seem to reme...
by KendalAstronomer
Fri Nov 09, 2007 10:30 pm
Forum: Observing
Topic: Major comet outburst by Comet P/Holmes
Replies: 254
Views: 71664

The pressure on the comet that produces the tail(s) comes from photons and solar wind particles striking the thing and evaporating stuff within it. Ionised particles are dragged out with the solar wind, producing a jet facing directly away from the Sun, and neutral particles evaporate away as the co...
by KendalAstronomer
Wed Nov 07, 2007 8:50 pm
Forum: General chat
Topic: What a lovely suprise!
Replies: 6
Views: 1659

by KendalAstronomer
Mon Oct 29, 2007 10:48 pm
Forum: Observing
Topic: Apparent Colour of Mars
Replies: 4
Views: 1766

In addition, the light is refracted by the air at lower altitudes (affected by wavelength dependant rayleigh scattering, which scaters red more than blue light) and also fog introduces Mie scattering (not quite so wavelength dependant, creates the haloes around lights in a foggy sky), which will mak...
by KendalAstronomer
Wed Oct 24, 2007 8:39 pm
Forum: Absolute beginners
Topic: Motor drive for Skywatcher
Replies: 12
Views: 3061

The offset between True North (the rotational axis) and Magnetic North (the magnetic axis on the compass) is known as the magnetic declination, and used to marked on maps. If you know your co-ordinates (can get them off www.multimap.com) and a good idea of your elevation, you can use something like ...
by KendalAstronomer
Tue Oct 23, 2007 10:44 pm
Forum: Absolute beginners
Topic: Motor drive for Skywatcher
Replies: 12
Views: 3061

Track in right ascension and tweak in dec if necessary. The RA-Dec co-ordinate system was devised so all the tracking motion occurs in RA.
by KendalAstronomer
Tue Oct 23, 2007 10:39 pm
Forum: Absolute beginners
Topic: I got First Light (and a couple of photography questions)
Replies: 3
Views: 1331

Plus it looks like the moon in that pic has been hit by Chromatic Abbaration (the light has been split a little, so the yellowish stuff is more prevalent on this part of the image, and I guess there'll be bluish stuff on the other edge of the moon (or the centre). This can be caused by the optics (c...
by KendalAstronomer
Mon Oct 22, 2007 8:01 pm
Forum: Space exploration
Topic: Diving from Space
Replies: 3
Views: 3796

Is it a half price round trip? EasyOrbit?