the night sky

pred · Posted: Tue Mar 13, 2012 12:44 am

I've noticed the last few days two bright objects in the sky, sort of WSW, they appear before any other stars but dissapear into the west, please someone tell me, are they planets or what.

sooey · Posted: Tue Mar 13, 2012 12:54 am

They've already been mentioned, it's venus and jupiter, the brightest one is venus.

pred · Posted: Tue Mar 13, 2012 1:08 am

sooey wrote:

They've already been mentioned, it's venus and jupiter, the brightest one is venus.

Thanks sooey, i've not been on here much lately and missed the post.

joinerjohn · Posted: Tue Mar 13, 2012 3:28 pm

Pred, tonight they appear closer in the night sky than they will for a long while. From now on their like me and my ex wife, drifting further apart.

squeaky · Posted: Thu Mar 15, 2012 8:16 pm

What is really weird is that as mentioned they are Venus and Jupiter together but Earth is between them

mickyg · Posted: Thu Mar 15, 2012 9:10 pm

if you have an iphone you can download apps like "nightsky" and "skywalk" which when pointed at stuff in the sky tells you what they are

Astra99 · Posted: Thu Mar 15, 2012 9:31 pm

You can also look at

http://www.astroviewer.com/interactive-night-sky-map.php

I have found "problems" using IE9, but Firefox is OK with it. It can take a minute or two for the command button "Start Astroviewer" to appear at the top left. Note that there is no need to download anything to your machine.

sooey · Posted: Mon Mar 19, 2012 1:05 pm

squeaky wrote:

What is really weird is that as mentioned they are Venus and Jupiter together but Earth is between them

Not at the moment it isn't, obviously.

imamartian · Posted: Mon Mar 19, 2012 9:23 pm

What is quite weird is how the Sun and all of the planets move in the same plane across the sky. And you can really understand why the ancients thought they all revolved around the Earth. The Sun very quickly, in fact once a day, and the other planets a lot less quickly, or just much further away.

Space cat · Posted: Tue Mar 20, 2012 3:32 pm

imamartian wrote:

What is quite weird is how the Sun and all of the planets move in the same plane across the sky.

It's not odd at all; the solar system formed out of a cloud of gas and dirt with angular momentum in it and it had a dominant axis of rotation. There had to be rotation or else the whole lot would have collapsed into a star without planets. (Somebody once told me that a star has to rotate as well or it won't be stable - but don't quote me on that.)

It's been too many years since I studied space dynamics but I can't quite see how a star system with orbits at random angles could come into being.

Susiejb · Posted: Tue Mar 20, 2012 3:37 pm

Space cat wrote:

It's been too many years since I studied space dynamics but I can't quite see how a star system with orbits at random angles could come into being.

Now I have never studied Space Dynamics SC but I think even I know that

sooey · Posted: Tue Mar 20, 2012 4:56 pm

I think you've misunderstood him susie.
If you think of a huge cloud with a small spin collapsing under its own gravity, as it collapses the spin will get faster and it will tend to flatten out.
The middle bit makes the star and the outer bits make the planets.
That's why planets orbit roughly in the same plane.

Susiejb · Posted: Tue Mar 20, 2012 7:04 pm

sooey wrote:

I think you've misunderstood him susie.
If you think of a huge cloud with a small spin collapsing under its own gravity, as it collapses the spin will get faster and it will tend to flatten out.
The middle bit makes the star and the outer bits make the planets.
That's why planets orbit roughly in the same plane.

ooo'er soooey..am I getting out of my depth here

I was just saying you obviously cant have stars going at random angles or they will crash whereas if they all go round the same way they don't.
But yes, having read your explanation I can see why they all orbit in the same direction.

sooey · Posted: Tue Mar 20, 2012 7:15 pm

It was me who misunderstood you.

I thought you were saying that you could see how a planetary system with random angles of orbits could happen.

Alarm · Posted: Tue Mar 20, 2012 10:18 pm

sooey wrote:

It was me who misunderstood you.

I thought you were saying that you could see how a planetary system with random angles of orbits could happen.

It does, to a degree. Explain comets?
Saturn and its moons.

Our moon for instance, the orbit is not a constant.
Our planet is not on a set orbit, but not too random...........but is constantly changing in relation to its orbit.

See the points, facts yet ?