Goodbye Manhattan, Welcome Back to Ithaca

We’ve been focusing on Manhattan for the past few months, with the aim to finish Season 4 and any remaining images of areas surrounding Manhattan in Season 1. We’ve made a big push in the last few months to finish Manhattan, and thanks to your help, we’ve completed all publicly released seasons of Manhattan.

With four seasons of Manhattan to add to the four seasons of Inca City that you’ve helped classify, we now have a rich dataset to start looking at how  geyser formation evolves over time and how the process of fans and blotch  changes from Mars year to Mars year.

Planet Four is  leaving Manhattan for now, but we’ll be back for Season 5 some time in the future. We’re going back to focus on another target of interest, Ithaca. We started classifying Ithaca Season 1 images last year, and they’re now back on the site for your to map fans and blotches.  You can learn more about Ithaca here. The most telling difference between Ithaca and other areas on Mars’ south pole is the giant fans.

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Dive into Ithaca today at

The Cerberus Fossae


The focus of this post will be on the area of the Martian surface that Planet Four: Craters volunteers have been marking craters on, the Cerberus Fossae.

The Cerberus Fossae is a set of west-north-west trending and almost parallel fissures or fractures that cut across the Cerberus plains on Mars. Evidence suggests that the fissures have been formed by faults that pulled the crust apart in the Cerberus region (9°N, 197°W).

Ripples seen at the bottom of the fault are sand blown by the wind. The underlying cause for the faulting was believed to be magma pressure related to the formation of the Elysium volcanic field, located to the northwest. The faults pass through pre-existing features such as hills, indicating that they are a young feature by the standards of those found on the surface.

In fact, this area of Mars has been identified as having the youngest volcanic plains on Mars. Early crater-counting efforts have suggested that the youngest lava surfaces in the area are less than 10 million years old. This is why it is of such interest to future missions to Mars, as a location where seismic activity might still be happening. To help predict the amount of seismic activity to expect, we need your crater markings to make a more accurate estimate of the age of the region.

If you have any other questions regarding some of the things you have spotted on Planet Four: Craters, please feel free to ask on Talk, and in the mean time please keep marking on!


Mark your calendars – 2 months until ZooCon 2015

Today officially marks two months until ZooCon 2015 hosted at the University of Oxford by the UK Zooniverse team.  It’s a day dedicated to volunteers and inspired by Zooniverse projects.

There will be some science team members (physically and virtually) from many of the Zooniverse projects talking about the recent progress and science results coming from your clicks. Some of the core Zooniverse team will be in attendance to give you updates on the latest news in the Zooniverse and where it is heading in the future.

After the afternoon discussions, attendees can later head over to a gathering at a local pub for a social evening. If talks aren’t your thing you can skip them and sign up just for the attending the pub event starting at 5pm, where you can meet  other Zooniverse volunteers and get to know some of the dedicated people who build and run the Zooniverse.

To give you an idea of what ZooCon is like check out this guest post  by our Talk  moderator Andy Martin (wassock), who attended ZooCon13. Also you can find the video of the ZooCon13 and ZooCon 14 Planet Four talks here and here. We don’t know if Planet four will be one of the projects featured (since there’s 30 projects to choose from!), but either way there will be lots of citizen science and Zooniverse happenings to talk about on July 11th.

ZooCon is set for Saturday,  July 11, 2015 from 13:00 to 21:00 (BST).There isn’t a published schedule of talks yet, but whether you’re interested in out of this world Zooniverse projects or ones closer to home, they’d love to have you join them in Oxford, UK. Tickets are free, but there is limited seating, so register if you want to attend. Reserve your spot today here.

Planet Four Season 2 and Season 3 Site Statistics

Are you ever curious to know how people classify on Planet Four? Well today is your day. I’m working on generating the final numbers for the first half of the Planet Four science paper in preparation. The paper is an introduction to the project and will contain the catalog of blotches and fans identified thanks to your help in Season 2 and Season 3. We’re getting closer to having the paper and the final catalog preparation in shape for submission by the end of the summer.

As part of the paper,  I wrote the section that talks about the classification rate and how people classify on the site. So I made a few close-to-final plots and calculated some relevant numbers from the classification database for Season 2 and 3 that will be included in the paper so I thought I’d share them here. These values and figures below are pretty close what will be in the submitted science paper.

We had a total of 3,517,363 classifications for Seasons 2 and 3 combined.  More blotches than fans were drawn, 3,483,724 blotches compared to  2,825,930 fans. With a total of 84604 unique ip addresses and registered volunteers who contributed to Planet Four when Season 2 and Season 3 titles were in rotation.  Most classifiers don’t log in. There is no difference between the non-logged in and and logged-in experience on Planet Four other than that if you classify with your Zooniverse account we can then give you credit for your contributions in the acknowledgement website we’ll make for the first paper, and we can only get your name (if you allow the Zooniverse to print it to acknowledge your effort)  if you classify with a Zooniverse account.

First plot shows the distribution of  the classifications for each tile in Season 2 and Season 3. You can see the impact of BBC Stargazing. Most of our classifications for Season 2 and Season 3 came from the period during and the few months after BBC Stargazing live and the site was getting lots of classifications and attention so we retired titles after more classifications than now. Currently a tile needs 30 classifications before we retire it, a number that better suits our current classification rate. You can see that nearly all of the Season 2 and Season 3 have 30 classifications or more, with a range of total classifications that we have to take into account when doing the data analysis and identifying the final set of blotches and fans from your markings since some tiles will have significantly more people looking at it than others.


The next plot shows the distributions of classifications for logged-in and non-logged in (without a Zooniverse account) classifiers combined for Season 2 and Season 3. We have a way to track roughly the number of classifications a non-logged in session does so I count them as a separate ‘volunteer’ in this plot (note I cut the plot off at 100 classifications for visibility). 

You can see that most people only do a few classifications and leave and there is a distribution and a tail of volunteers who do more work. That’s typical of the participation in most websites on the Internet About 80% of our classifications come from people who do more than 50 classifications, typical of many Zooniverse projects.  Both the people that contribute a few clicks and those that contribute more are valuable to the project and help us identify the seasonal features on Mars. So thanks for any and all classifications you made towards Season 2 and Season 3, and if you have a moment to spare today there’s many more images waiting to be classified at


Tiles and Full Frame Images

I thought I’d go into a bit more into detail about what exactly you’re seeing when you review and classify an image on Planet Four.  On the main classification site we show you images from the HIRISE camera, the highest resolution camera ever sent to another planet.  Looking down from the Mars Reconnaissance Orbiter, HiRISE is extremely powerful. It can resolve down to the size of a small card table on the surface of Mars. The camera is a push-broom style where it uses the motion of the spacecraft it is hitching a ride on to take the image. During the HiRISE exposure,  MRO moves 3 km/s along in its pole-to-pole orbit , which creates the length of the image such that you get long skinny image in the direction of MRO’s orbit. The camera can be tilted to the surface as well, which can enable stereo imaging.

The HiRISE images are too big to show the full high resolution version in a web browser at full size. The classification interface wouldn’t quickly load, as these files are  on the order of ~300 Mb! – way too big to email.  But the other reason is that the full extent of a HiRISE full frame image is too big and zoomed-out for a  human being to review and accurately see all the fan and blotches let alone map them. So to make it easier to see the surface detail and the sizes of the fans and blotches,  we divide the full frame images into bite-sized 840 x 648 pixel subimages that we call tiles.


An example Planet Four Tile

For the Season 2 and Season 3 monitoring campaign, a typical HiRISE image is associated with 36-635 tiles When you classify on the site, you’re mapping the fans and blotches in a tile. Each tile is reviewed by 30 or more independent volunteers, and we combine the classifications to identify the seasonal fans and blotches. To give some scale, for typical configurations of the HiRISE camera, a tile is approximately 321.4 m long and 416.6 m wide. The tiles are constructed so that that they overlap with their neighbors. A tile shares 100 pixels overlap in width and height with the right and bottom neighboring tiles.  This makes sure we don’t miss anything in the seams between tiles .

If you ever want to see the full frame HiRISE image for a tile you classified, favorited, or just stumbled upon on  Talk, there’s an easy way to do it. On the Talk page for each tile we have a link below the image called ‘View HiRISE image’ which will take you to the HiRISE team public webpage for the observation, which includes links to the full frame image we use to make tiles plus more (note= we use the color non-map projected image on Planet Four). Try out this example on Talk.

So next time you classify an image and recall how detailed it is, remember that although it’s just a small portion  of the observation, your classifications are hugely important. Without them we wouldn’t be able to study and understand everything that’s happening in the HiRISE observations. It’s only with the time and energy of the Planet Four volunteer community that we are able to map at such small scales and  individually identify the fans and blotches., which is crucial for the project’s science goals. So thank you for clicks!

Crater Features

Since the launch of Planet Four: Craters a few weeks back, we have had several Talk posts regarding different features and markings that have been spotted in and around the craters themselves. This post will go through what some of these markings might be, and hopefully answer some of the questions you have had!

Recurring Slope Lineae (RSL)


Recurring slope lineae are narrow, dark markings found on steep slopes (like crater edges) that incrementally lengthen during warmer periods, then fade over cooler seasons and can recur over multiple Martian years. They can grow to be several hundred metres in length, and it has been suggested that they are caused by wet flow – originating from melted ice.

Active Gullies


Martian gullies are small networks of narrow channels, along with their associated down slope deposits, that occur on steep slopes, especially on crater walls. It has been suggested that they are formed by a flow of dry material, supported by a layer of dry ice just below the surface.

New Impacts

new impact

As the name suggests, these are craters that have been formed by impacts that have occurred in the near past. They are found all over the surface of Mars, and although they vary in size the smaller ones are much more frequent. They can be spotted by the darker coloured ejecta formed around them (due to the disturbed surface material that has yet to settle), or in some cases the presence of brighter patches – indicating where subterranean ice has been revealed.

If you have any other questions regarding some of the things you have spotted on Planet Four: Craters, please feel free to ask on Talk, and in the mean time please keep marking on!


Goodbye Inca City, Onward to Manhattan

Thanks to your help, the Inca City images we’ve been showing on the site for the past several months are complete, and we’re now back in the region known as Manhattan. We’ve been to Manhattan before, but that was during a different Martian year. HiRISE has been in orbit around Mars for almost 10 Earth years which equates to roughly 5 Martian years.  We’re showing new never-before-seen images on the Planet Four website right now. These observations are taken from HiRISE’s 4th Martian spring imaging the development of the windblown fans.

By examining the same region over and over again during different Spring seasons, we can study how this process of forming fans and geysers is evolving over time and how properties like topography, thermal inertia of the soil, presence of different types of spider channels, and changes in the Martian atmosphere impact the properties of the seasonal ice sheet and thus the formation and evolution of the seasonal fans (and by proxy the geysers that form them). In addition, the fan directions and lengths, as well as the presence of blotches, are an excellent probe of wind direction and strength throughout the Martian Spring. With your classification we will be able to see if the winds repeat the same each season or change direction.

For the rest of the South Pole we only have observations from Season 2 and Season 3 classified. With the completion of the previous set of Inca City images, we now have four seasons of fan formation mapping in Inca City. The extra two seasons doubles the temporal baseline we have on Inca City to look for changes and evolution in the fan formation process. The classifications you make now will help us have the same kind of dataset for Manhattan. Having fan and blotch maps for two regions with different topography and locations on the Martian South Pole will help us tease out which effects are due to local conditions and which ones are due to to the changes in the Martian climate (like more dust in the ice sheet).

Help classify the new images of Manhattan at

PS.  If you haven’t tried out Planet Four: Craters, do take a look and classify an image or two. Your classifications and feedback will help improve  the design of future Zooniverse projects.

Plane Four: Craters

Welcome to Planet Four: Craters!

Recently, a new version of the Planet Four project went live, and we are asking you to mark craters on the surface of Mars.

By counting the craters we will be able to figure out how old various geological surfaces are! This will be a big help for missions such as the 2016 NASA InSight experiment, which will use geophysical techniques such as seismology and heat flow to figure out how Mars has evolved. Knowing the age of the surface will help us to put a time-scale on that evolution.

Another aim of the project is to help improve the design of future Zooniverse sites.

When marking craters on Mars using this new version of Planet Four, you will be using one of three different classification interfaces. They each have different tools for you to use (on the left hand side of the page), and will ask you to complete tasks in differing orders for each image. Don’t worry! When you use one of these interfaces for the first time a tutorial will guide you through how to use it, in the same way the original Planet Four site did.

The reason for the different interfaces is that we want to know which one works the best, the one that you enjoy using the most and find the easiest to use, and gives the best crater marking results.

To find this out, we would really value your feedback. If you have a spare 15 minutes, there is a questionnaire on the Talk page (accessed through clicking the discuss button on the classify page) where you can answer questions and give your opinions about using the interfaces.

The information you give us will then be used to help design future versions of Planet Four, and other Zooniverse projects – so your opinions really count!

Get involved now at

Happy crater marking!


Clustering the PlanetFour results

Our beloved PlanetFour citizen scientists have created a wealth of data that we are currently digging through. Each PlanetFour image tile is currently being retired after 30 randomly selected citizens pressed the ‘Submit’ button on it. Now, we obviously have to create software to analyze the millions of responses we have collected from the citizen scientists, and sometimes objects in the image are close to each other, just like in the lower right corner of Figure 1.


Figure 1: Original HiRISE cutout tile that is being shown to 30 random PlanetFour citizen scientists.

And, naturally, everybody’s response to what can be seen in this HiRISE image is slightly different, but fret not: this is what we want! Because the “wisdom of the crowd effect” entails that the mean value of many answers are very very close to the real answer. See Figure 2 below for an example of the markings we have received.


Figure 2: Original markings of P4 Citizen scientists.

Note the amount of markings in the lower right, covering both individual fans that are visible in Figure 1. It is understandable that the software analyzing these markings needs to be able to distinguish what a marking was for, what visual object in the image was meant to be marked by the individual Citizen scientists. And I admit, looking at this kind of overwhelming data, I was a bit skeptical that it can be done. Which would still be fine, because one of our main goals is wind directions to be determined and as long as every subframe results in the indication of a wind direction, we have learned A LOT! But if we can disentangle these markings to show us individual fans, we could even learn more: We can count the amount of activity per image more precisely, to learn how ‘active’ this area is. And we even can learn about changes of wind direction happening, if at the same source of activity two different wind directions can be distinguished. For that, we need to be able to separate these markings as good as possible.

And we are very glad to tell you that that indeed seems possible, using modern data analysis techniques called “clustering” that looks at relationships between data points and how they can be combined into more meaningful statements. Specifically, we are using the so called “DBSCAN” clustering algorithm (LINK), which allows us to choose the number of markings required to be defined a cluster family and the maximum of distance allowed for a different marking before being ‘rejected’ from that cluster family. Once the cluster members have been determined, simple mean values of all marking parameters are taken to determine the resulting marking, and Figure 3 shows the results of that.


Figure 3: Clustered markings for P4 tile ZG7

Just look at how beautifully the clustering has merged all the markings into results have combined all the markings into data that very precisely resembles what can be seen in the original data! The two fans in the lower right have been identified with stunning precision!

For an even more impressive display of this, have a look at the animated GIF below that allows you to track the visible fans, how they are being marked and how these markings are combined in a very precise representation of the object on the ground. It’s marvelous and I’m simply blown away by the quality of the data that we have received and how well this works!


Figure 4: Animated GIF for the clustering of the markings of APF0000zg7

This is not meant to say though that all is peachy and we can sit back and push some buttons to get these nice results. Sometimes they don’t look as nice as these, and we need to carefully balance the amount of work we invest into fixing those because we need to get the publication out into the world, so that all the Citizen scientists can see the fruit of their labor! And sometimes it’s not even clear to us if what we see is a fan or a blotch, but that distinction is of course only a mental help for the fact if there was wind blowing at the time of a CO2 gas eruption or not. So we have some ideas how to deal with those situations and that is one of the final things we are working on before submitting the paper. We are very close so please stay tuned and keep submitting these kind of stunningly precise markings!

For your viewing pleasure I finish with another example of how nicely the clustering algorithm works to create final markings for a PlanetFour image:


Figure 5: Animation for the clustered markings process of P4 image ZMJ

2 Years On from BBC Stargazing Live

In the UK, tonight starts the latest installment of BBC Stargazing Live. Three nights of live astronomy television hosted by Professor Brian Cox and Dara Ó Briain.  Just over two years ago, we were preparing for the launch of the Planet Four live on television as part of Stargazing Live. Professor Chris Lintott from the BBC’s  Sky at Night and PI of the Zooniverse went out on the program broadcast live from Jodrell Bank and introduced to the world Planet Four,  asking for viewers help to map the seasonal fan and blotches visible in images of the Martian South Pole taken by the HiRISE camera.

For the past 9 years, the HiRISE camera aboard the Mars Reconnaissance Orbiter has been capturing stunning and dynamic images of the defrosting South Pole. During this time, carbon dioxide geysers loft dust and dirt through cracks in a thawing carbon dioxide ice sheet to the surface where it is believed that surface winds subsequently sculpt the material into dark fans observed from orbit. 30% of Mars’ atmosphere condenses out to form this ice sheet. Understanding the direction, frequency, and appearance of these fans (a proxy for the geysers) and how these properties are impacted by varying factors we can better understand the Martian climate and how it differs from Earth.

This is a project that we truly couldn’t do with out the help of citizen scientists and BBC Stargazing Live. Hundreds of thousands of fans are visible in HiRISE observations, but for years this rich dataset was not tapped to its full potential. Automated computer algorithms have not been able to accurately identify and outline individual fans in the HiRISE images,  but a human being intuitively can distinguish and outline these features. And thus Planet Four was born.

I can remember launch day like it was yesterday, waiting on the Talk Discussion tool for the flood of volunteers to start posting questions and sharing their thoughts and ideas about the images they were seeing. I and the rest of the Planet Four team anxiously waiting at our keyboards could tell immediately when the Planet Four segment aired. The response from Stargazing was incredible and overwhelming. Each night, the Zooniverse servers struggled to keep up serving images of Mars as the number of people on the site continued to rise. Thanks to the Stargazing Live viewers we were able to complete nearly all of the Season 2 and Season 3 HiIRSE monitoring campaign images.

So where are we now? Thanks to help of Planet Four volunteers including Stargazing Live viewers, we’ve made great progress since January 8, 2013. Over 4.6 million blotches and 3.8 million fans have been drawn to date (the great majority of these markings were made during BBC Stargazing Live). In the past two years, Planet Four has captured the equivalent of a full year of non-stop human attention (a single person working non-stop/no breaks for an entire year!). The science team has been working to create a software pipeline to combine the multiple classifications to identify fans and blotches. We have also been working to create an expert dataset classified by the science team for a very small subset of Planet Four images to compare to the volunteer classifications to  show that  Planet Four citizen scientists are very efficient and effective at detecting the seasonal fans and blotches in the HiRISE images.

I’m pleased to say the science team is very close to submitting the project’s first science paper to a journal before the end of the year (we’re aiming for end of Spring/Summer). We have more than half of the paper draft currently written. One of the last lines of the paper is:  ‘We thank all those involved in BBC Stargazing Live 2013.’ This is just the beginning. With this paper, we’ll be able to eventually  produce the largest areal coverage wind measurement of the Martian surface to date spanning two Martian years. These maps will reveal how the fan properties and numbers change from Martian year to year and location to location on the South Pole. We also have 3 more Martian seasons of HiRISE data that we’ve just barely scratched the surface of. The majority of these images have yet to be classified, including right before a Martian dust storm, so we can see how the dust storm has impacted the Martian climate and how long its effects last in the atmosphere and  the ice sheet by looking at the fans and geysers that are created in the seasons before and after the storm

This year the Zooniverse has something new up their sleeve that will be revealed during the broadcast, but while you’re waiting for the return of BBC Stargazing tonight, if you can spare a minute or two , we could use your continued help mapping the seasonal fans visible in the HiRISE images. There is so much of the South Pole (and 3 additional years of data to get through) that we have yet to study and explore! Classify a HiRISE tile or two at


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