Venus through the telescope

[JBR1194]

Hello

I recently purchased a new celestron telescope and set it up last night to use for the first time. I live in UK, around 8/9pm-ish I took my telescope outside to view Venus in the western sky as it was v bright, perfect opportunity.

After finding Venus and increasing the focus I realised that there was something like a large black circle in the centre of the bright blue/white ring of light. Before focussing, it appeared to be just v bright light. 

I am wondering if anyone can explain to me why this black circle appeared on / in front of Venus.  I thought it looked like a moon, which is obviously incorrect but it looked that way. Is it possibly sulphuric clouds of Venus absorbing light? 

Any information/help is much appreciated

happy observing, all!

Edited March 5, 2020 by JBR1194

[knobby]

HI, the black ring indicates you were probably out of focus, Venus will appear as a very small but really bright dot in most scopes. If seeing is good and you can focus accurately you should be able to make out the phase (not round, a bit like the various Moon phases)

[Ruud]

Hi, welcome.

What you saw was the shadow of the secondary mirror. That happens when you are way out of focus. You tried to use the focus knob as a zoom knob. It can't zoom though, only focus or blur.

When you reach focus, blur is minimal and the planet will look as small as it gets through the telescope (same for stars: sharper is smaller). You'll see that Venus has a gibbous phase, slight more than half.

---

The Moon was out. An easy way to test if you are focused properly is to have a look at the Moon: if that is sharp, the rest of the sky should be too. For practical purposes everything out there is at infinity.

 

Edited March 5, 2020 by Ruud

[JBR1194]

That's great information thank you very much Knobby and Ruud.

I need to get used to this, will try again tonight

thanks again!

[Space Hopper]

Venus looked great through my scope on Monday night when i was last observing and Its phase was clear to see.

Current phase is just over 60% and decreasing day by day.

I always like to follow it as it approaches us in its orbit ; watching the crescent get bigger and narrower as it approaches IC.

 

[RobH2020]

On 06/03/2020 at 19:27, Space Hopper said:

Venus looked great through my scope on Monday night when i was last observing and Its phase was clear to see.

Current phase is just over 60% and decreasing day by day.

I always like to follow it as it approaches us in its orbit ; watching the crescent get bigger and narrower as it approaches IC.

 

 I'm new to observing Venus too, and I'm not clear how sharp i should be able to get it. 

So far I've been able to see the phase but it's pretty blurry with a 6" f8 dob. Do i need to wait for better seeing, collimate better, or is that all i can hope for?

Thanks!

[Space Hopper]

If it's blurry its probably a case of letting your scopes optics cool for a bit.

Its pretty high in the sky at present : about as good as it gets, so atmospherics should be less of a problem.

[Stu]

8 hours ago, RobH2020 said:

 I'm new to observing Venus too, and I'm not clear how sharp i should be able to get it. 

So far I've been able to see the phase but it's pretty blurry with a 6" f8 dob. Do i need to wait for better seeing, collimate better, or is that all i can hope for?

Thanks!

Try observing it as early as you can when it is highest and against a lighter sky. Thus tends to reduce the flaring and glare you often get when it is dark. Cooling and collimation do help too of course so get these as good as you can.

[IanL]

It will be a lot smaller than you are probably expecting. To give you a rough idea, below are are couple of images of Venus and the Moon that I took a bit over a week ago - both with the same scope and camera, so effectively the same "magnification". Venus should look like a tiny 'half Moon' at the moment when you have it in focus, but as you can see it is way smaller than the actual Moon. It will become more like a crescent Moon over the coming weeks.

Edited March 9, 2020 by IanL