Archive | May 2011

Let the voting begin…

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












Jules is a volunteer moderator for the Moon Zoo forum


One Year on the Moon

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)

LPOD image

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.

LROC image

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)

credit NASA

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.


Have fun and happy hunting.

Moon Zoo Forum

Additional  news links:

Moon Zoo featured on BBC (at18:20 min)
From NASA JPL, Moon Zoo Telecon
From Scientific American

Thomas J is a volunteer moderator for the Moon Zoo forum.

Chains of Craters

Most of the time, craters occur randomly across planetary surfaces. They may seem to occur in clumps or clusters, groupings or voids, but because craters usually form from an extraplanetary impactor striking the surface, there is no preferred location on a planet.

This is one reason that actual chains of craters are interesting features that some people like to study. Chains of craters will usually form in one of two ways. The first is through a process that is endogenic – meaning that it is produced by forces on or within the planet itself. These are known as “pit craters” and form overtop an evacuated lava tube when the surface collapses into it. We see these on Earth in regions of volcanism like Hawai’i where we even have “Chain of Craters Road” on the Big Island. We also observe these all over the major volcanic regions of Mars. And, they are present on the moon.

An aerial (left) and ground-based (right) view of the “Devil’s Throat” pit crater on the Big Island of Hawai’i. Image courtesy USGS.

Very large pit craters on the flanks of Ascraeus Mons on Mars. Image from THEMIS data (ASU).

Since Moon Zoo users are asked to identify impact features, it’s the second type that we’re more interested in: Secondary crater chains. Secondary craters form when an extraplanetary impactor strikes the surface, creates large, cohesive blocks of ejecta, and these blocks strike elsewhere on the surface and create their own craters. Hence, they are secondary to the primary impact (astronomers are not that creative in naming things). Because of the way material is ejected, these can occur randomly spaced around the primary impact, in clumps, or in long chains. We ask you to identify crater chains in Moon Zoo in part to identify regions of secondary craters.

Chains of secondary craters. Small white dots indicate secondary craters that are larger than about 1 km in diameter. Image from CTX data (Malin Space Science Systems).

Secondary Craters on the Moon

Chain of secondary craters. Image from LROC NAC data (ASU) and found by our forum member Tom128.

Understanding secondary craters is one of the “new old frontiers” in crater populations research. Secondary craters were first identified by a fairly famous planetary scientist named Eugene Shoemaker (remember Comet Shoemaker-Levy 9 that hit Jupiter in 1994?) in the early 1960s based on telescopic and early space-based photographs of the moon. The opinion of secondary craters – whether they are statistically important at a given size, how many are produced, how they are produced, the pre-requisites for their production, and their populations – has varied widely throughout the last half century in the planetary community. In fact, secondary craters were generally ignored. Until recently.

Over the last several years, interest in secondary craters has picked up after a pair of papers in 2005 that identified 10s of thousands of secondary craters produced across Jupiter’s moon Europa from a single large impact (Pwyll), and identification of 100s of millions of secondary craters from a single, young impact crater on Mars (Zunil). (The papers are Bierhaus et al. (2005) and McEwen et al. (2005).) These began to reignite debate in the planetary geology community about how important secondary craters are in crater populations.

This is still an open debate. People generally fall into three or four camps. The first would be those who say that secondary craters don’t really exist at all except in localized areas. Very few people actually believe this. The second is that secondary craters exist, affect crater statistics, but that on a surface with a large number of craters the “background” secondary crater population is generally uniform and we don’t have to make any special consideration for them. The third is that secondary craters are important, are non-random, and need to be taken into account when using craters for most applications. A fourth potential camp is that they are important but are hopelessly tangled with the primary crater population so there’s “no use crying over spilled milk,” as the saying goes. I personally fall mostly in the third camp and a little in the second.

But, a better understanding of secondary craters is one of the main science goals of Moon Zoo. Helping to identify chains of craters – one of the few ways secondary craters appear on a planetary surface – is an important step in this goal. After all, we can’t really study them if we don’t know where they are! Many large secondary craters are known over the lunar surface, such as those produced by the relatively “youthful” Mare Orientale (roughly 3.8 billion years old) (see image below). With Moon Zoo, we’re asking you to look at very small-scale, meter-sized features as opposed to 10s of kilometers, and there is simply too much of the lunar surface for planetary scientists to do it all.

Large crater chains emanating radially from Mare Orientale on the Moon. The white lines are drawn above the chains so you can still see them. Image from LROC WAC mosaic (ASU).

So next time you’re identifying features on the moon, take a moment and look for any kinds of crater chains. Post them in our forum. If you’re adventurous, take some time to explore the lunar surface on your own with the wonderful ACT-REACT tool made available by the Lunar Reconnaissance Orbiter Camera (LROC) team. For more information on how to use it, see this helpful thread on our forum. Posting permalinks from the ACT-REACT tool is a fast and easy way to draw attention to a particular region and allows us to extract the relevant images and use them in our next round of Moon Zoo images.