Humans love a good space story. That's why it's so much fun to speculate about unusual objects seen in images of Mars. Our imaginations turn rock formations into faces and cosmic rays into alien communications. A recent image from the Mars Curiosity rover generated plenty of online speculation about what looks like a crab-shaped object tucked into a dark cranny. Is it an alien crab monster? Not likely. It's probably just a weird rock formation.
Join us as we explore some famous Mars mysteries and the scientific explanations behind them.
NASA's Viking 1 Orbiter zipped near Mars in 1976 and took this now iconic image of the surface. What got everyone excited is the face-like formation in the upper center of the picture. If you have a creative mind, it's easy to see it as having two eyes, a nose, a mouth and a weird hairdo. It even looks a bit like a young Elvis Presley. You can see why some people thought the face was an alien-built monument on Mars.
First published August 4, 2015.
Updates June 21, 2017: Adds images including a strange Martian pit, a trippy mesa and an "alien" kissy face. Dec. 6, 2017: Adds images including "blueberries," spherules and gullies. Mar. 19, 2018: Adds images including dragon scales, stick-like figures and an avalanche. Dec. 3, 2018: Adds images including Mars volcano, Beaker, Pac-Man, lava coils and a shiny object.
NASA wasn't going to let the face on Mars go without an explanation. The Mars Global Surveyor cleared things up for good in 2001 by taking a fresh image of the face. The newer, sharper, higher-resolution picture shows a much blobbier, less stark formation. In short, it's just a mesa and not an alien-carved religious site.
Mark one up for the funny-bone file. NASA's Curiosity rover sent a photo back to Earth in 2014 that showed a very odd rock shaped a bit like a femur bone from a human thigh. Scientists obligingly explained that the unusual shape was most likely the product of erosion by wind or water. If NASA ever did amazingly find human remains on Mars, scientists would want to shout it from the rooftops.
This view from NASA's Mars Reconnaissance Orbiter, snapped in February 2016, shows some strange formations on the surface of the red planet. The dark, raised areas are a series of dunes that look a lot like the dots and dashes of Morse code.
Unfortunately, the code spells out gibberish. Planetary scientist Veronica Bray analyzed the dune image and told Gizmodo the code works out to read "NEE NED ZB 6TNN DEIBEDH SIEFI EBEEE SSIEI ESEE SEEE !!"
NASA finally solved the jelly-doughnut mystery by announcing that the rock's sudden appearance was the result of the rover dislodging it by driving over it. Sadly, NASA has still not discovered snacks on Mars.
There's nothing edible here. These hematite-rich spherules are known by the cute nickname "blueberries." NASA's Mars Opportunity rover spotted the small, BB-sized pebbles in 2004 near the Fram Crater.
NASA/JPL-Caltech/Cornell Univ./ USGS/Modesto Junior College
A collection of spheres
Opportunity got a good look at hematite-rich "blueberries" in 2004, but it also picked up a view of this unusual formation in 2012 at an outcrop named Kirkwood.
"The spherules at Kirkwood do not have the iron-rich composition of the blueberries. They also differ in concentration, distribution and structure," NASA says. The space agency calls them "puzzling." You can see the work of erosion on some of the tiny spheres.
NASA/JPL-Caltech/Univ. of Arizona
A tadpole on Mars
Admittedly, this formation spotted by NASA's Mars Reconnaissance Orbiter looks a lot like a tadpole or even a yo-yo or sperm. In actuality, it's a circular crater, but the tail has been carved out by water movement.
"We can infer that water is flowing outward because we have the necessary terrain-height information," the space agency said in February 2018. While the planet had a long-distant watery past, it doesn't currently host any amphibian life as far as we know.
A peculiar jet appears far back in this scenic Mars landscape photo taken by NASA's Opportunity rover in 2016. It's actually a dust devil, much like we experience here on Earth. Towering dust devils are weather hazards on Mars and they're something future human visitors will need to be prepared to handle.
In December 2017, A popular blog for UFO enthusiasts posted a close-up look at this spherical object spotted by NASA's Curiosity rover and suggested it was a cannonball left over from a war on the red planet. NASA's rover team responded with a Twitter message pointing out how the concretion is less than a quarter inch (5 mm) in size and is actually made up of calcium sulfate, sodium and magnesium.
NASA/JPL/University of Arizona
A cloud of particles puffs upward at a steep cliff in this 2010 image from NASA's Mars Reconnaissance Orbiter. This isn't the sign of a factory on Mars, but instead is "likely the result of an avalanche or fall of mostly carbon-dioxide frost." According to NASA, this sort of event happens mainly during the planet's springtime, which roughly corresponds to April and early May on Earth.
NASA/JPL-Caltech/University of Arizona
Waffle-shaped island on Mars
The Mars jelly doughnut didn't work out, but NASA wasn't done with food-shaped formations on the red planet just yet. An image from the Mars Reconnaissance Orbiter from late 2014 showed a strange waffle-shaped island on the planet's surface. The 1.2-mile-wide feature is located in an area of lava flows. It's not evidence of waffle irons on Mars, but it might be the result of lava pushing the formation up from below.
Even NASA gets excited for Game of Thrones, which is a good explanation for why the space agency described this Mars Reconnaissance Orbiter image as "Dragon Scales of Mars."
The scaly pattern doesn't come from a mythical creature, but rather through ancient landscape processes involving erosion. "The nature of the water responsible for the alteration, and how it interacted with the rock to form the clay, remains poorly understood," NASA said when it released the evocative image in July 2017.
Shiny object on Mars surface
Everybody likes shiny things. We like them even more when they pop up seemingly out of context on faraway planets. That happened in 2012 when NASA's Curiosity rover spotted a bright, shiny object tucked into the dull Martian soil. For perspective, the entire image covers an area just 1.6 inches across. NASA scientists confirmed the tiny bright bit is simply part of the geology of Mars.
Take a look at the center of this image from NASA's Curiosity rover. You might see a long-handled spoon stretching out over the landscape, casting a shadow below. Is this a sign that cooking is a popular hobby on Mars? Unfortunately, no. Mars doesn't have the same pull of gravity we have on Earth, so fragile formations like this one have a chance of holding up and not just crumbling down to the ground.
In 2017, NASA's Mars Reconnaissance Orbiter looked down and snapped this image of a bizarre-looking formation in a region known as Noctis Labyrinthus, which translates to "labyrinth of the night." The wavy areas around this mesa are sand dunes.
NASA's Curiosity rover sent back a curious photo in 2014 showing a blip of light on the horizon of Mars. The image excited UFO fans, who speculated about the light's source, wondering if it might be evidence of alien activity.
NASA scientist Doug Ellison rained on the extraterrestrial parade with the explanation that the blip was likely caused by a cosmic ray hit, the result of high-energy particles flying through space.
The Mars Curiosity rover has been at the center of quite a few unusual-object sightings on the red planet. A famous incident occurred in 2012 when the rover noticed a shiny object on the ground that didn't match its surroundings. Speculation ranged from jokes about Jimmy Hoffa's cufflink to it being an AOL CD. The explanation turned out to be pretty benign when NASA announced the object was a small plastic piece of the rover itself that had fallen off.
That weird shiny object spotted by NASA's Curiosity rover had an anticlimactic explanation. It was just a shred of plastic from the rover itself. This close-up image comes from the rover's ChemCam and helped NASA scientists determine the origin of the Martian interloper. NASA described it as "likely benign," which should leave the door open just enough for us to image the presence of a human-hungry alien race hiding out on the red planet.
NASA's Spirit rover delivered an image in 2007 showing a view of craggy little rock formations across the surface of Mars. One dramatically shaded formation stood out in the form of what looked like a little walking humanoid (either that or Bigfoot).
The Curiosity rover Twitter account shared a look at these formations in January 2018 and got a lot of snarky speculation in return. Twitter users suggested the stick figures looked like everything from tire tracks to Viking runes.
In October 2016, NASA's Curiosity rover spotted a weird little iron meteorite during its explorations around the base of Mount Sharp in the Gale crater on Mars. The rock would look small sitting in the palm of your hand, but the rover's close-up view shows the intricacies of the meteorite's surface. Researchers named the meteorite Egg Rock.
NASA posted this Mars Reconnaissance Orbiter image in March 2018 with the dramatic title "The Case of the Martian Boulder Piles." Look past the dark slug-like sand dunes and instead contemplate the open spaces. It contains a surprisingly orderly series of boulder piles.
NASA scientists suggest the neat piles could have been caused by a "frost heave" process with freeze-and-thaw cycles pushing the rocks into tidy shapes. A similar process has been observed here on Earth.
President Donald Trump makes a cameo appearance on Mars in this 2009 image from NASA's Opportunity rover that hit the news in 2016. It's an excellent example of pareidolia, the same psychological phenomenon that lets us see dragons or rabbits in clouds. The rock does bear a resemblance to him, complete with over-swept hair.
There's more than one woman-shaped rock on Mars. This image from the Mars Curiosity rover excited alien theorists earlier in 2015. The small, shadowy object inside the red circle does look a little bit like a statuette of a lady in a dress. All it takes is a strong imagination.
NASA's Mars Curiosity rover snapped a photo that could have blended in with a hundred other Mars photos in July 2015. However, this particular photo earned itself a measure of infamy when a Facebook group enhanced a close-up of one tiny piece of the picture and unveiled what looked like a weird crab monster hiding out in the shadows. It could also pass as Cthulhu.
Ultimately, the crab creature of Mars is just a fun interplay between light and shadow. It's still just a rock formation at heart.
It's fun to imagine what aliens on Mars might look like if they were real. You might conjure up images of big heads and large, black eyes, or perhaps something with crazy tentacles and sharp teeth. UFO enthusiasts imagined a bigger, hairier version of alien life when they spotted what looked like a Sasquatch skull among the landscape debris on the red planet.
The image comes from NASA's Curiosity rover from early 2016. Squint and you can imagine the random rock looking a bit like a skull with a round dome and a large eye socket. Is it really a Bigfoot skull? No. It's still just a rock, but hopefully it'll inspire some fun sci-fi stories about the great Sasquatch of Mars.
On the left is a cropped view of an image from the Mars Opportunity rover. On the right is a Neo-Assyrian attendant god statue from the British Museum. Notice a little resemblance? So did some UFO fans, who brought attention to the face-like rock found on the red planet.
As with all Mars rocks that look like Earth objects, it's really a combination of human imagination and fortuitous light rather than a sign of an alien civilization with a penchant for carving sculptures.
The European Space Agency's ExoMars mission suffered a setback when its Schiaparelli lander crash-landed Mars in October 2016. NASA's Mars Reconnaissance Orbiter took this photo of the crash site to help ESA investigators work out what happened to the ill-fated lander. The large dark spot shows the impact site. Other highlighted areas show the front heatshield, parachute and rear heatshield.
These distinctive-looking round shapes are found in the Eagle Crater on Mars. Take a close look at the one on the upper right-hand side. Notice a small dot inside? That's the lander that carried the Mars Opportunity rover down to the planet's surface in 2004. A small dot toward the lower left-hand corner of the image is the lander's backshell and parachute.
NASA shared this fresh view of the landing gear in the crater in April 2017.
This strange landscape photo might remind you of worm tracks or some strange ant farm. What you're actually seeing here is a 2016 Mars Reconnaissance Orbiter view of Mars' south pole.
"The polar cap is made from carbon dioxide (dry ice), which does not occur naturally on the Earth. The circular pits are holes in this dry ice layer that expand by a few meters each Martian year," NASA explains.
NASA/JPL-California Institute of Tecnology; Flickr/2di7 & titanio44
Not an alien hunk of metal on Mars
Some Mars-watching space fans on Flickr enhanced an image captured by the Mars Curiosity in early 2013 to highlight what appears to be a hunk of metal just hanging out on the red planet's surface. The likely explanation is a lot less fun than imagining a race of metal-forging aliens. The object is probably a piece of a meteorite or the result of strange lighting. It's definitely not an alien fertility effigy.
NASA's Curiosity rover got up close to investigate this interesting shiny object in November 2018. The Curiosity team suspected it might be a meteorite, but didn't want to say for sure without confirming the identification by examining the rock's composition.
Wakka, wakka, wakka. NASA's Mars Reconaissance Orbiter caught sight of this Pac-Man imagery on Mars in early 2018. The shape of the retro video game star appears thanks to an impact crater with a crescent-shaped barchan sand dune inside.
These lovely spiral patterns aren't petroglyphs. The swirls are known as lava coils. "When two lava flows in opposite directions mingle and swirl, the coils are the hardened results," says the University of Arizona team that works with the HiRise camera on the Mars Reconnaissance Orbiter.
NASA/JPL/University of Arizona/Red circle by Amanda Kooser/CNET
Beaker on Mars
Mee-mee-mee-mee. A familiar Muppet face appeared on Mars in this mid-2018 image from NASA's Mars Reconnaissance Orbiter. The formation in the south pole region resembles Beaker the lab assistant from The Muppet Show. The southern polar cap is covered with frozen carbon dioxide and is full of pits and mesas that can take on unusual shapes.
The European Space Agency's Mars Express orbiter snapped this Mars view on Sept. 24, 2018. Some people who saw the image thought it might show an active volcano smoking on the planet's surface. What we're actually seeing is a cloud that happens to have formed near the Arsia Mons volcano. There's no eruption here.