Petavius Rille

[Nightspore]

I know this entire forum isn't really intended for visual astronomy, but on the off-chance there are any visual astronomers reading this, The Petavius Rille may be visible this evening. This rille feature is only highlighted well by the terminator when the Moon is between 12~15% illuminated. The rille itself is probably best viewed between two to four days after the New Moon.

 

 

At 21:00 today the Moon will be at about 30° altitude although by 22:30 it will be less than 18°. I would recommend yellow, orange or yellow-green filters for twilight viewing as these not only improve contrast but help darken the background sky. 

 

 

Petavius is a large *impact crater in the vicinity of the Sea of Fecundity. It has a large double rimmed outer wall, and is around a hundred and eighty kilometres in diameter. There are central mountains that are nearly two kilometres in height. The large rille feature itself is a hundred and ten kilometres across. 

 

*There are some theories that it is volcanic in origin.

 

Images by courtesy of SkySafari Pro

Edited May 4, 2022 by Nightspore

[TerryMcK]

All aspects of astronomy are welcome. If it is clear here tonight I'll have a gander. Thanks for the heads up Dave.

[Nightspore]

21 minutes ago, TerryMcK said:

All aspects of astronomy are welcome. If it is clear here tonight I'll have a gander. Thanks for the heads up Dave.

 

You're welcome. I'm not sure if the twilight will be a problem, a Wratten #21 or #15 might help. The difficulty with the Petavius Rille is that you have to catch it at just the right time. If the terminator is too far away it will be bleached out. 

 

Speaking of visual astronomy, it might be useful to have more subsections under 'Visual observing at night'. Possibly along the lines of:

 

Lunar/Planetary Observing

Deep Sky/Rich Field Observing

 

Mercury may also be visible tonight around 20:40, but I think it will be a bit low for me. It may possibly be observed earlier with a telescope but you have to be very careful not to accidentally look at the Sun.

[TerryMcK]

7 minutes ago, Nightspore said:

 

You're welcome. I'm not sure if the twilight will be a problem, a Wratten #21 or #15 might help. The difficulty with the Petavius Rille is that you have to catch it at just the right time. If the terminator is too far away it will be bleached out. 

 

Speaking of visual astronomy, it might be useful to have more subsections under 'Visual observing at night'. Possibly along the lines of:

 

Lunar/Planetary Observing

Deep Sky/Rich Field Observing

 

Mercury may also be visible tonight around 20:40, but I think it will be a bit low for me. It may possibly be observed earlier with a telescope but you have to be very careful not to accidentally look at the Sun.

Good idea. I've created a couple of pinned topics that will remain at the top of the Visual Observing At Night section

[TerryMcK]

I saw the crater quite clearly through my 20x80s binocs but sadly not enough mag on these binos to see the rille. I toyed with dragging the dob out but now clouded over.

[Nightspore]

2 hours ago, TerryMcK said:

I saw the crater quite clearly through my 20x80s binocs but sadly not enough mag on these binos to see the rille. I toyed with dragging the dob out but now clouded over.

 

Yeah, I think you probably need at least 40-50x to see the rille. I could see it at 70x quite distinctly.