2 questions

[Steve1976]

Hi guys and girls

I have two subjects which I'm hoping you all can help me with.

The first relates to Venus - as I understand it Venus has phases much like the moon. So when does the next crescent phase start? Will Venus become bigger during this crescent phase?

The second relates to galaxies in and around Ursa Major - particulary M81 and M82. According to Turn Left at Orion now should be a good time to sneak a peak at them but I'm finding it just so uncomfortable looking up at things nearer the zenith - so much so that I think I could easily have broken my own neck the other night! Any tips for a more comfortable search?

Cheers

[mdstuart]

M81 and M82 are very good at the moment. In fact when they are overhead they are at their brightest as you are looking through less atmoshere...But it is an issue to see things at the zenith with certain scopes...

Lower down?? Try M65/66 in Leo which is at a more suitable angle.

Mark

[russ]

The second relates to galaxies in and around Ursa Major - particulary M81 and M82. According to Turn Left at Orion now should be a good time to sneak a peak at them but I'm finding it just so uncomfortable looking up at things nearer the zenith - so much so that I think I could easily have broken my own neck the other night! Any tips for a more comfortable search?

In thoery M81/82 are perfectly placed as they are directly overhead in the darkest part of the sky with the thinest part of the atmosphere. But trying to see them up there is not easy. A right angle finder certainly helps to nail them in a comfortable position but you still need to check the scope is pointing in the right direction. Also, an EQ mount is a right pain in backside when looking directly upwards. The best bet is a dob with a right angle finder or just wait until they are placed a little lower.

[Ant]

As Venus moves into the evening it comes out from behind the Sun.

As it moves out to the East (setting later and later after the sun), the phase is decreasing and the size is slowly increasing as well.

When it reaches it's furthest (angular)m point from the sun it is roughly at "First Quarter", it gets slowly bigger and thinner as it closes into the sun again...

Here is a sequence of images that I took 2 years ago (they are to scale).

It'll be a few months yet before Venus reaches the "First Quarter" stage.

Hope that helps.

Ant

[Demonperformer]

The first relates to Venus - as I understand it Venus has phases much like the moon. So when does the next crescent phase start? Will Venus become bigger during this crescent phase?

Venus is currently moving towards us from the other side of the sun (superior conjunction; 11/1/10). It is getting bigger, but the phase is getting smaller as it moves towards us.

On 20 August, it will be at maximum elongation and will show a 50% phase, but will not be particularly well-placed to view from the UK.

It will continue to show a narrower phase, but bigger disk as it continues to approach us, but it is now moving closer to the sun. It passes the sun on 29 October (when it would look like a new moon if you could observe it then - don't try:)).

It will then appear in the morning sky as a narrow phase and will start to pull away from us to the other side of the sun again. The mornings of Nov/Dec should be a really good time to observe Venus, you won't be able to mistake it in the dark morning skies. During these two months its phase will grow to 24%, but its size will shrink from 54" to 42".

Hope all that makes sense to you.

Ant got in ahead of me!

[Steve1976]

Venus really does get significantly bigger then!!!

As always thanks for the replies folks.

I did kind of give up on M81 and M82 and made an attempt at finding the galaxies in Leo but again I had no success. I think a combination of lack of experience and a fairly bright moon. Hey ho! I will keep trying!

Did manage to bag M51 a few nights ago but it was lower down off course (a personal first!)

[EA2007]

Try a diagonal mirror with your scope for Bode's galaxy and the Cigar galaxy.

As for Venus...yeah it appears larger. The smaller the crescent the closer it gets to us.