1

Physics, Astronomy & Cosmology / What did I see?

« on: 18/07/2009 16:50:03 »

About a week ago I awoke around 3:15 GMT (just before dawn) and noticed a very bright object around due south about 25 degrees above the horizon.  At first I thought it was Venus even though it was much brighter than I had ever seen the planet. After a few a few minutes I again peered out and was surprised to see the object had faded to about half it's previous brightness. Since it appeared stationary I wondered whether it was a super nova - but after a few more minutes I went back to sleep. It was not a dream as my wife also saw the object. Later in the day I checked the position of Venus and promptly discounted this as the cause. For the last few days this has perplexed me until I realised that the direction of the observation coincides with with geostationary TV satellite positions. The following night (to the annoyance of my wife) I set the alarm for the same time - you guessed it - no sign of anything near the location where seen.

Is it possible that I saw a direct reflection from the solar panels of a geo sat?  does anybody have any other possible explanations?

2

Physics, Astronomy & Cosmology / Effect of nuclear explosions in space?

« on: 02/06/2009 21:14:04 »

I am a little puzzled by the idea of destroying comets using nuclear war-heads. As far as I can tell nuclear explosions occur on earth by merely producing an intense burst of energy which superheats the atmosphere, and thus causes rapid expansion of the air, after a few seconds cooling begins and the atomic 'wind' reverses in direction. In addition to this there is the intense heat/light radiation across a wide spectrum.  apart from possibly melting the surface of a comet/asteroid can anybody explain why so many people think a nuclear explosion would disintegrate such an object?

Conventional explosives (black powder derivatives excluded) detonate ie turn from a compact solid into gas and thus produce a real blast wave, using conventional explosives would be far more effective.  Of course I might have missed something in my understanding,   discuss?

3

That CAN'T be true! / Water stories.

« on: 26/05/2009 10:37:06 »

Some Mineral water (in the UK) firstly claims to be 60 million years old then suggests
it should be sold by a specific date (usually within 6-8 months)

I guess they got that out of the ground just in time!

Know anymore obscure sell-by / best before stories?

4

Just Chat! / Freudian Word Link

« on: 15/05/2009 21:26:35 »

THe rules:  only ONE word per post, read the word then post your immedate thought!

First word:-

GUMBALL

5

Physics, Astronomy & Cosmology / What is the temperature in space?

« on: 14/05/2009 22:03:24 »

I heard it again, and it really gets to me,

"The astronauts experience a temperature change from +200C to -200C"  - BOllocks"

The temperature of space is NOT 10 or 50 or 100 Kelvin, it is space, it has no temperature.
Temperature is a parameter of matter, it's about how atoms wobble about!, space does not wobble about!

When an astronaut does a space walk energy from the sun is absorbed by his/her suit and may indeed raise the temperature then, when in shade, heat will be radiated from the suit but like a vacuum flask heat is only lost through radiation and not convected or conducted away.

There, I got that off my chest! now who agrees with me?

6

That CAN'T be true! / Latest news on Stephen Hawking.

« on: 14/05/2009 17:36:43 »

He has now left hospital, having been admitted with a broken nose, two broken wrists, a broken ankle and shattered jaw after his girlfriend stood him up.

7

Guest Book / new to all this.

« on: 14/05/2009 15:46:23 »

Hi,

I recently retired and have become interested in science, I can answer all sorts questions on stacking shelves, selling kitchens, microwave ovens etc so go ahead and ask!

8

Physics, Astronomy & Cosmology / How far back in time can we see with powerful telescopes?

« on: 14/05/2009 15:04:18 »

Being a really thick bastard I'm having a bit of hubble trouble, that is, I am told the hubble has produced pictures of the universe as it was some  12.5 billion years ago, or about 1 billion years after it formed.

It seems to me that if this is the case then we maust have been travelling away from that point almost as fast as light since that time.

Or to put it another way,

Suppose I let off a flash-bang grenade then travel at light speed for 13.5 million years then as I stop and look back I will see the flash as it occured 13.5By ago - this is doing my head in....