Over the last couple of weeks I’ve had a bash at explaining a few things (simply) and I’ve tried to keep it in ‘layman’ terms.
The Moon - First Quarter (Day 7)
Over the last couple of weeks I’ve had a bash at explaining a few things (simply) and I’ve tried to keep it in ‘layman’ terms. There’s a danger in over simplification of distorting fact into fiction (god only knows we see it often enough in every day reporting) but I’ll do my best not to do that. Thank the ‘Mystery’ that other learned people write excellent works for us to learn from and I for one applaud them. It must be great to still have all you’re ‘bit’s’ working.
The Rings sometimes seen around, The Moon.
These rings are seen on nights when we have a very high layer of thin cloud. There maybe (indeed, often is) other layers of cloud below the higher layer. The temperature up there in the thin layer of cloud , usually ‘Cirrus’ is extremely cold and the Ring is caused by light shining through six (6) sided ice crystals suspended within those clouds. This Ring usually has a diameter of around 22o degrees and was seen in the heavens over Townsville (Australia) recently – early May 09. There can also be an outer Ring which extends out to around 44o degrees. This is an incredibly pretty event, so keep looking up, you never know! Farmers on the land have been known to put great stock in the idea that rain often follows this phenomenon and indeed I can remember my own Grand Father saying (after witnessing a ring around the Moon) ‘there’s rain on the way’, we’ll plant tomorrow! He was right more often than not.
You know! For a small lump of badly beaten rock in our heavens (about ¼ the size of Earth) the moon certainly has a lot to do with our daily lives. Sadly our little friend is slowly but surely getting further away. In the early days of it’s existence the Moon would have been seen to be larger and the days on Earth shorter (had we been around to see it) but it is in fact moving away at a few centimetres a year (about 3 or so). So in the far distant future (millions of years) the days on Earth will be a fair bit longer. A total eclipse will no longer be the total block-out it is now as the Moon disc will not fit the suns disc as well as it does at this time. It’s amazing just how exact everything seems to be now regards the Earth, Moon and Sun and in all our travels to come we may never see it this good, again.
All right, enough on that. Let’s get down to Day 7 on the Terminator, mind you Day 7 next lunation will most probably look just a ‘tweeny’ bit different due to libration but you make minor adjustments for that as you go and there is information available in AS & T Magazine (Australian Sky & Telescope), every month.
Now for today’s topic:
Ok! The first quarter is complete and we can now see all of the ‘Maria’ in that quadrant with the exception of ‘Mare Frigoris’ which will continue to reveal itself over the next few days. However, the moons little ‘wobbles’ can, on occasion reveal a fair portion of the eastern side of ‘Mare Imbrium’ on Day 7, thus giving us a really good look at the mountains separating it from it’s eastern cousin ‘Mare Serenitatis’. We’ll cover them in their turn in future articles.
We’ll begin at the southern ‘cusp’ of the moon and although different optics present the Moon to our eyes in different aspects, it doesn’t take long to figure out which is the highland end of our target. There are a few small craters here worth a look but I won’t mention all of them, at this time. ‘Curtius’ is a reasonable subject to get us going with a diameter of 95km and the Sun touching it’s western edge. ‘Cuvier’ 78km, ‘Heraclitus’ 97km and ‘licelus’ at 76km make a tight threesome well worth a few minutes. Down the Terminator a short distance to a couple of larger craters. These are ‘Maurolycus’ inland about half a day with a diameter of 116km and ‘Stofler’ at 126km. ‘Stofler’ is interesting because it has itself been impacted a few times – the largest impact being ‘Faraday’ at 72km.
‘Aliacensis’ and ‘Werner’ make a very nice target with their steep, deep sun lit walls. These two (2) come in at 81km and 71km respectively. Now, I think we’ll bypass some more of the smaller craters to list them all would require many hours and result in quite an ‘atlas’.
We come then, to a really big fellow with its central mountain peak kissed by the sun and a smaller impact sitting on its western edge. ‘Albategnius’ is a huge 134km across and along with it’s smaller companion ‘Klein’ 44km it has several tiny impact points and the western edge is somewhat damaged. ‘Hipparchus’, another very large crater at 153km is just to the north along the terminator and shows wall damage on it’s south western edge and also has a small central peak and impact sights within, one of which is ‘Horrocks’ at 30km, a sharp, neatly defined crater.
‘Godin’ at 36lm and ‘Agrippa’ at 46km are a nice little pair inland a short distance and surrounded by ‘Hyginus Rille’ to the north-west at 220km long (better on Day 8) and ‘Ariadaeus Rille’ at 250km which borders the eastern edge of ‘Mare Vaporium’. This Mare is also marked on the eastern edge by a very white, fresh looking crater known as ‘Manilus’ at 39km. It also stands out nicely on the Full Moon, Day 15 and the word ‘fresh’ is descriptive only, as this crater is really quite old in the scheme of things.
‘Silpicius Gallus’ is one of the smaller ones at 12km and is situated on the southern floor of ‘Mare Serenitatis’. Further along to the north is a really small crater and a challenge to spot. It is one named ‘Linne’ and comes in at a very small 2km (larger scopes perhaps would be better in the pursuit of really small blemishes). Out to the terminator from there we have two (2) really astounding mountain ranges. They are the ‘Appennine Mountains’ and the ‘Caucasus Mountains’. The ‘Appennine Mountains’ form the boundary, or part there of, ‘Mare Imbrium’ separating it from ‘Mare Vaporum’ and ‘Sinus Aestuum’ in the south-east and south respectively, while the ‘Caucasus Mountains’ separate ‘Mare Imbrium’ from ‘Mare Serenitatis’ in the north-east. These ranges are better covered on Day 8 but are really up to close scrutiny as they show themselves on Day 7.
On to the North now where we have a really sharp little crater that goes by the name of ‘Calippus’ 31km diameter embedded in the northern end of the ‘Caucacus Mountains’. A little further down we see two (2) craters set as a pair. There are a few pairs such as these but set in different aspects and areas. They make for good viewing and give ‘the viewer’ something to compare other nearby craters to. The first of our pair is ‘Eudoxus’ at around 67km and set just to the north of the ‘Caucasus Mountains’. In the rugged foot hills, so to speak, the second of the two is a somewhat larger crater a little further to the north again and named ‘Aristoteles’. It comes in at about 88km and like it’s partner is an exceptional example of wall terracing, caused by time and also very similar to another nearby pair from Day 5 in ‘Hercules’ and ‘Atlas’. ‘Aristoteles’ sits up tight in the south of ‘Mare Frogoris’ on Day 7 and leaves only a couple of small craters to go for this viewing. The first is a small fellow named ‘Sheepshanks’ at 30km (yes, I know folks, the name floored me too) and then to ‘C Mayer’ at 38km.
Well people, that brings to an end another enjoyable trip down the ‘Terminator’. It’s a very busy part of the Moon and I think it offers some of the best viewing available on the lunar surface. So dust off the scopes and enjoy!
My usual thanks must go to my friends at:
www.Astrovisuals.com.au – for top Moon Maps (also available on CD).
www.myastroshop.com.au – for ‘Exploring the Moon’ by Steve Massey, exceptional paper back.