Fresh white impact craters are the most recent impacts on the Moon. Anything less than a billion years old (which means it is from the current Copernican era), is considered young in lunar terms. Some may be very young indeed. There are very few large craters with the bright ray systems associated with fresh craters. Tycho is thought to be the youngest large crater unless a group of 12th century astronomers were right and this accolade should go to the far side crater Giordano Bruno.
They are important because their ejecta blankets are as fresh as they were on the day of the impact and have not been disturbed by micrometeorites. Many of these craters have extensive ray systems and in some cases ejecta was flung out for hundreds of kilometres (in Tycho’s case 1500 km stretching to the Apollo 17 landing site in the Taurus-Littrow region.) Landing sites for robotic or manned missions can, therefore, be chosen to take advantage of this to maximise the different types of rock available to analyse. You don’t have to go to Tycho to see what Tycho is made of. Analysis of the Tycho ray samples brought back by the Apollo 17 crew show Tycho to be around 100 million years old.
The rays of a fresh crater can be spectacular to view through binoculars or a telescope when the sun is overhead with respect to the crater so full Moon is the best time to observe them. The rays look white not because the rocks excavated are bright white in colour but because their newly exposed and broken surfaces are clean and shiny and have a relatively high albedo in comparison to the mature, darker mare material they lie on top of which has been battered and dulled by micrometeorite impacts.
So why is Moon Zoo interested in them? There are several reasons.
- By counting the number of fresh impact craters the team can calculate the current impact rate of the Earth-Moon system which is of interest for assessing the risk of asteroid and meteoroid impacts.
- Also small fresh, impact craters of of just a few kilometres in diameter are the most likely locations from which lunar meteorites found on Earth have been ejected and pinpointing the source of these meteorites is the subject of much research.
- And because fresh craters are undisturbed their crater walls, interior features and secondary craters can be studied in detail.
Forum member Tom128 developed an interest in freshly formed craters and started a forum thread to collect “Great Fresh Whites.” Here are some of the early finds:
And there is more information in the Fresh White Crater Reference Resource here.
Jules is the volunteer Moderator of the Moon Zoo Forum
Here’s a reminder the Moon Zoo science goals- and what our clicks are being used for.
1. To improve our knowledge of the production of small lunar craters by gathering information about their numbers and dimensions. This can be used to improve lunar maps and coordinates.
2. To calculate the age of different lunar surfaces (e.g., mare, impact melt sheets, highland crust) by comparing the number and sizes of impact craters. The more cratered a region is the older it is. Knowing the age of different surfaces allows us to build up a history of the geological processes on the Moon, in particular its temporal thermal and magmatic history. What we learn about these processes on the Moon we can then apply to other small rocky planetary bodies.
3. Results from Moon Zoo could also assist in the development of automated computer crater counting systems, and to help understand how image viewing geometries influences crater counting studies.
4. To determine variations in lunar regolith thickness by assessing the presence of boulders around crater rims.
5. To identify unique and unusual morphological features that help us to better understand the geological diversity of the Moon. Recording these featured will help to develop a database of interesting morphological features (for example, boulder tracks, fresh white and dark haloed craters, crater chains, elongate craters and pits etc) for the lunar science community to use.
To produce a boulder density hazard map to assist in identifying suitable landing sites for future human or robotic lunar missions.
- To produce peer-reviewed science.
- To promote lunar and planetary science through using Moon Zoo as an educational and public outreach tool.
- To identify small, highly elliptical craters that may have preserved meteoritic material.
- To assess degraded craters according to variations in user measurements and produce maps of crater degradation states.
NAC Strip: M170877942RE Latitude: 9.4 Longitude: -48.3 (close to Marius V crater)
After finding the fresh white crater on the NAC strip I did a bit more exploring and found a crater with a good example of “black stuff” – see the TLP Project – Black Stuff for more information.
“Black Stuff” – same NAC strip as above.
The Marius Hills region of the Moon is full of interesting formations and contains many volcanic domes, cones and rilles, and is well worth exploring.
I looked at a wider view of the area using the ACT-REACT tool and discovered the Rima Suess rille which runs for about 200 km across this region. There is a strange elongated “craterlet” to the north-west of the rille which appears to be connected to it in some way. I can’t find much information about this craterlet and it would be interesting to know how it formed and if it is related to the Rima Suess at all.
from ACT-REACT tool. Craterlet is at Latitude: 8.65 Longitude: -48.66
Every now and then Moon Zoo produces an image that just needs to be shared. Forum regular kodemunkey found another fresh white crater a while ago. I say another one because the forum contains many examples of these eye-catching recent impacts. And when I say recent I mean these impacts are millions rather than billions of years old. So it’s easy to be a little blasé when yet another one is posted. Until one comes along which hits you between the eyes. We featured one last year. And now we have another – a small unnamed crater on the western edge of Mare Vaporum. Click on the image for a bigger, better view.
Here it is in context – one small crater amongst many. The Lunar Reconnaissance Orbiter picked it out and highlighted its symmetrical beauty.
The impact produced some lovely feathery ejecta patterns (which are worth exploring even closer on the NAC images) and a gloriously bumpy and bouldery crater floor. Follow the links above (and this additional resource) for more information on fresh craters or just click on the first image, click again to zoom and sit back and enjoy.
Around many large craters, smaller secondary craters can be found caused by falling debris from the main crater forming process. Secondary craters can appear in clumps, sometimes in a herringbone pattern, or more unusually in a line – a crater chain. We haven’t found many crater chains in Moon Zoo. This is probably because they tend to be large features and best spotted using a wide view. Some chains have distinct separate craters while others look indistinct and decidedly fuzzy. Using the ACT-REACT Quick Tool forum regular kodemunkey found a great example of a fuzzy crater chain north of Mare Orientale.
The fuzzy “landslide” effect is due to fragments of debris from the originating impact landing one after the other very close together in a line. The impacts and ejecta have interfered with each other resulting in a string of wispy densely-spaced secondary craters.
A closer look at ACT-REACT shows that the terrain slopes upwards from left to right and that the chain is just over 1km long. The elevation graph shows the expected dips where the debris has impacted.
So where is the parent crater? Secondary craters fall radially to the original impact and up to hundreds of kilometres away. I think the most likely candidate is an unnamed fresh white crater 100 km away.
We have featured crater chains before as Image of the Week. They are fairly illusive but make striking images when you find one. And if you do find one, whether distinct or fuzzy, don’t forget to post it on the forum thread.
Previous Crater Chain Images of the Week:
We are used to seeing different kinds of craters on the Moon Zoo forum. In particular we collect dark haloed craters and fresh white craters. Impacts can excavate rocks and material beneath the lunar regolith and this “fresher” material forming the ejecta blanket sometimes looks a very different colour to the rest of the surrounding area due to its higher or lower albedo.
Forum member kodemunkey recently found a couple of impacts which at first glance were hard to classify – you could say they were impacts of two halves. Are they fresh whites or dark haloed? Or is it just a trick of light and shadow? I think that’s exactly what we are seeing in the first crater. The combination of a high Sun, uneven terrain and a deep impact has produced an image of a crater half in shadow. The second crater is slightly more difficult to call. Both make striking images. Why not have a closer look and see what you think.
Last week Moon Zoo moderator Thomas presented us with a superb selection of images from the first year of Moon Zoo. Now it’s time to vote for your favourite. Browse the images below to remind yourself and pick out the one you like the most. Pop over to the forum and cast your vote. You’ll need to create a zooniverse account if you don’t already have one – it’s the work of a moment so go on, do it! Voting ends Tuesday 24 May. The winning picture will be announced soon after and we’ll hunt down the best resolution version we can find so you can have a nice new desktop image!
MAY 2010 INA
JUNE 2010 CARO’S TADPOLE
JULY 2010 GREAT FRESH WHITE
AUGUST 2010 FRACTURES
SEPTEMBER 2010 MOON BRIDGES
OCTOBER 2010 ARISTARCHUS
NOVEMBER 2010 AWESOME CRATER
DECEMBER 2010 DAGUERRE CRATER
JANUARY 2011 SOUTH RAY CRATER
FEBRUARY 2011 STRIPY BOULDERS
MARCH 2011 TYCHO
APRIL 2011 CAVES
Jules is a volunteer moderator for the Moon Zoo forum
This week, Moon Zoo celebrates its first year since launch back in May 2010. Initially designed as a way to count and measure craters, the simple ‘point and click’ interface was an inspired idea allowing users to mark out craters seen in high resolution images of the lunar surface. The addition of a tool to ‘flag’ interesting features, objects and locations has provided some great discussion and superb image posts to our forum.
We’ve hunted down and rediscovered the ‘Apollo’ and ‘Lunar’ landing sites in unprecedented detail, searched for lost spacecraft debris and followed miles of boulder tracks. Our hunt for the ‘weird and wonderful’ has revealed stunning volcanic vistas, beautifully defined features and intricate crater chains. Recent work on the forum, using new tools and techniques, has allowed us to study the lunar surface at oblique angles revealing yet more lunar mysteries and, equally, more questions.
For this special ‘Image of the Week’/Blog I have decided to take a retrospective look at the last year, recounting some of the amazing features and locations posted on the forum. I would like to post every image from our weekly slot but I’ll choose one of my personal favourites from each month.
I hope you enjoy them as much as I do.
From our first Image of the Week in May 2010 The volcanic caldera ‘Ina’.
Ina (named after a lunar goddess in Polynesian mythology) is an odd looking “D shaped” lunar geological feature about 2 kilometres wide which was first spotted by the Apollo Astronauts. (Jules)
Moon Zoo image
June 2010 Caro’s Tadpole.
Posted by Caro as something odd and maybe a possible crater chain, it is rich in detail and looks a little like a tadpole complete with a tail. (Thomas)
July 2010 Great Fresh Whites.
Fresh white impact craters are the most recent impacts on the Moon. Anything less than a billion years old (which means it is from the current Copernican era), is considered young in lunar terms. (Jules)
August 2010 Deep Seated Fractures.
Could they help us in the hunt for Transient Lunar Phenomena (TLP)?
September 2010 Moon Bridges
This is the King Crater Bridge from LROC image number M113168034R (Jules)
October 2010 The Aristarcus Region.
Aristarchus crater was named after the Greek astronomer Aristarchus of Samos by an Italian mapmaker called Giovanni Riccioli. The crater is relatively young, being formed approximately 450 million years ago and is one of the brightest craters on the nearside with an albedo almost double that of other similar features. (Geoff)
November 2010 Awesome Crater.
This crater was found by user mercutin and posted in the Crater Questions thread on 4th November 2010. I downloaded the LRO strip containing the crater and extracted the following image. (Geoff)
December 2010 Dark ejecta from Daguerre Crater.
A stunning picture of the dark material spreading out in a ray pattern and also cascading over the crater wall towards the crater floor. (Tom128)
January 2011 South Ray Crater
South Ray crater is about 2 million years old and the Apollo 16 astronauts returned samples from this area for analysis back on Earth. (Geoff)
An image stitched together by Moon Zoo forum member Bunny Burton Bradford
February 2011 Stratified Ejecta Blocks.
Another hunt….and this time it’s stripy! (jules)
Katie Joy from the Moon Zoo team says: We would like you to take a closer look at large boulders in Moon Zoo images. We want people to spot boulders that have layers cutting across the rock.
Forum members Half65 and Tom128 found these examples of stratified bouders in Aristarchus.
An example posted by Geoff
March 2011 Tycho.
Appropriately named after one of the most colourful characters in astronomy, Tycho Brahe, Tycho is one of the most prominent craters on the Moon with its large, bright ray system dominating the southern hemisphere. (Jules)
And here’s a close up of the rugged crater floor. (Jules)
April 2011 Potential Caves and Sink Holes in Copernicus Crater.
I came across one good candidate on the floor of Copernicus Crater (JFincannon)
Moon Zoo users have now classified 2,087,029; an area of 48,348 square miles or 206.6 Chigacos within the first year. With more images to come and fresh locations to search, I look forward to another successful year of discovery and learning as we reveal more of our closest neighbour.
HAPPY BIRTHDAY MOON ZOO!
Have fun and happy hunting.
Additional news links:
Thomas J is a volunteer moderator for the Moon Zoo forum.
Forum member jaroslavp was presented with this Moon Zoo image a few weeks ago:
ID: AMZ1001i8l (Nr Apollonius on the edge of Mare Spumans / Mare Fecunditatis)
Intrigued by the elongated shape of the crater he went on to investigate and what he found posed us all with an interesting crater conundrum. jaroslavp commented that the marked crater looked very different under different solar illumination. In one image it looks like any other round crater. In the other it looks very elongated and is surrounded by bright material.
|NAC image: M111219210LE Incidence angle 35.13
||NAC image: M119482862RE Incidence angle 57.64
Moon Zoo Team Science member astrostu was impressed and thought this was an excellent example to use to highlight the effect that different angles of solar illumination can produce.
jaroslavp wondered if the round crater was actually new, maybe a recent meteorite impact: He said:
“Maybe the crater wasnt there before? When I look on the dark spot there is no sign of the crater we can see on the second picture. And maybe the sun 45° from the surface makes many things invisible that you can see on the dark picture for example fresh white and dark-haloed craters.”
After some forum discussion it became clear that this really is just the result of viewing the same crater under different illumination but it certainly got us thinking and it is the best example yet we have had on the forum of just what a difference lighting can make as this animation jaroslavp put together shows:
Now on a roll, jaroslavp then found another strange crater containing a chain of 4 smaller craters and noticed something on the right hand slope of the crater wall:
ID: AMZ10018h5 (Taurus Mountains region)
So – is the small chain of secondary craters overlying the featured crater from a different crater impact or from the same impact that created the host crater?
Every day something intriguing is posted on the forum. It’s a great place to discover the Moon!
Jules is a volunteer moderator for the Moon Zoo forum
Kaguya – NASA
Forum regular JJ went hunting for the Japanese lunar explorer Kaguya impact site. Kaguya (or SELENE: SELenological and ENgineering Explorer) was launched 14 September 2007. Once in lunar orbit Kaguya released two smaller satellites into separate elliptical polar orbits: Okina (a relay satellite for communications) and Ouna (a Very Long Baseline Interferometry (VLBI) radio source satellite for supporting radio measurements). As well as its 2 sub-satellites Kaguya carried 13 scientific instruments including a lunar Magnetometer, a Gamma ray spectrometer, a Lunar Radar Sounder and an Earth-looking Upper Atmosphere and Plasma Imager. the mission lasted 18 months after which Kayuya was sent into a series of lunar orbits prior to a controlled impact on 10 June 2009. The impact site was conveniently in darkness at the time allowing the impact flash to be seen from Earth. Okina impacted on the far side on February 12 2009. Ouna is still in orbit.
The Kaguya mission amongst other things has improved lunar global topography maps (also used by Google to make Google Moon 3D), a detailed gravity map of the far side, and the first optical observation of the permanently shadowed interior of south pole Shackleton crater.
The Kaguya impact coordinates are well documented but we couldn’t recall seeing a high resolution view of the impact site from LRO. What JJ was looking for was a small fresh impact which would have exposed some fresh lunar regolith leaving a white scar with a blackened centre where debris may remain.
The Kaguya website gives the impact coordinates as E80.4, S65.5. Here’s the location:
This indicates an impact site on the wall of an unnamed crater near crater Gill. Part of crater Gill is top left of this image provided by ESA:
Using the ACT-REACT Quick Map tool JJ located the unnamed crater.
And found a likely impact site on the rim of a smaller crater within the unnamed crater.
And finally – a potential impact site with a centre geodetic diameter of 23m:
We think it’s definitely a contender.