Fact of the day..

[mdstuart]

I found out that our sun is pretty weak compared to those in the sky we look at with the Naked eye.

As I understand it..if you take our sun 50 light years away you would not be able to see it...

So Pleides the cluster is 400 light years. At that distance our sun would be WELL below visibility so the stars in Pleides are FAR brighter than the sun..

I think eta cassiopea os like our sun but is 20 light years away but other than that there are not many other brightish G main sequence stars you can see..

Mark

So tommorrow someone else please come up with a fact of the day that is not well known...

[Gannymede]

nice fact

[lukebl]

The best way to compare its real brightness is to use its absolute magnitude, i.e the magnitude at a distance of 10 parsecs (32.6 light years)

At that distance the sun would be just mag. +4.8. By comparison, Rigel would be mag -8, Deneb -7.2 and Betelgeuse -5.6. Sirius would be mag +1.4. Proxima Centauri would be just +15.5

[Peter Drew]

When trying to explain to some of the general public the size of the Sun, which to them looks the same as the Moon, I find it helpfull to say that if the Earth was placed at the centre of the Sun, the Moon's orbit would be 200,000 miles below the surface!

[umadog]

It's also useful to tell them that you could line up 110 earths along the diameter of the sun's disk. If you're projecting the sun or using a solar scope then you can use the sun-spots as comparison. Often these are larger than earth.

[Telrad]

Interesting, definitely food for thought..

[Mr Spock]

If Rigel was at the same distance as Alpha Centauri it would be as bright as the moon.

[Stevie816]

Gravity always wins

It's like chocolate, no matter how far away it is it has an effect on you and you are drawn towards it once within a certain distance there is only one outcome Chocolate never repels (Quote "Science for Girls")

[lukebl]

If Rigel was at the same distance as Alpha Centauri it would be as bright as the moon.

And, of course, if Betelgeuse was also as close as Alpha Centauri, we would be toast sometime in the next million years.

[661-pete]

When trying to explain to some of the general public the size of the Sun, which to them looks the same as the Moon, I find it helpfull to say that if the Earth was placed at the centre of the Sun, the Moon's orbit would be 200,000 miles below the surface!

Talking about the size of the Sun and the Moon, here's a little test which anyone can check out for themselves, although the answer will catch some people out!

Which of the following objects, when held out at arm's length, will just about cover the Moon and no more?

1. A pea.

2. A hazelnut.

3. A walnut.

[LukeSkywatcher]

That would be a pea.

[661-pete]

That would be a pea.

Of course. I don't suppose many experienced stargazers would be stumped, but apparently there's a widespread belief amongst 'lay' observers that the Moon is a lot bigger than it really is.

I recall, there was a TV programme many years ago, in which Patrick Moore was standing on a beach with a bunch of teenagers, and asked each of them, without looking at the Moon first, to pick up a pebble that would fulfil the above test. He was the only one to choose a pebble of the right size.

[mdstuart]

Great facts everyone!

Mark

[kniclander]

if the 200" hale telescope were the size of the united states the biggest "hill" would be about 4 inches high. smooth

[glowjet]

Whats in a name, ever heard of : Lode Star, Alruccabah, Cynosur, Phoenice, Tramontana, Angel stern, Navagatoria, Star of Arcady, Yilduz, Mismar, Polyarnaya, Dhurva, to top it all it is a Cepheid variable. What is it ? its Polaris of course by other names, its a good job the rest of the stars don`t have as many names