Bearing a striking resemblance to a stark British shoreline, this image is actually of an inverted crater on Mars: https://t.co/YzviPvT6x7 pic.twitter.com/sYelqJ2SD9

— NASA (@NASA) June 25, 2017

It's been awhile since I dropped a thread o' #Mars, so let's try something different today... pic.twitter.com/LtXRbFhQJ7

— Tanya Harrison (@tanyaofmars) July 14, 2017

1. The hues of #Mars' surface are generally thanks to dust cover—or (relative) lack thereof. Lighter areas = dusty, darker = less dusty. pic.twitter.com/EbsyOsVYVk

— Tanya Harrison (@tanyaofmars) July 14, 2017

4. Mars has huge volcanoes, including Olympus Mons, the tallest in the Solar System. But none have been active for >100 million years. pic.twitter.com/jLtCkBo4Rt

— Tanya Harrison (@tanyaofmars) July 14, 2017

6. Valles Marineris is often called the largest "canyon" in the Solar System. But it's actually a series of "chasmata." (Img: @Cornell) pic.twitter.com/5ycU3yUnvz

— Tanya Harrison (@tanyaofmars) July 14, 2017

14. Mars's surface is red due to iron oxide. But if you get below the rusty dust, it's often not red at all! pic.twitter.com/PtQ9UKFAJu

— Tanya Harrison (@tanyaofmars) July 14, 2017

15. When Spirit's right front wheel stopped working, it serendipitously dug a trench that exposed nearly pure silica—evidence of past water. pic.twitter.com/SlIjQCZGYb

— Tanya Harrison (@tanyaofmars) July 14, 2017

17. Newly-formed impact craters on Mars blast away the dust on the surface around them, revealing the underlying darker nature of Mars. pic.twitter.com/MM3VCtP8cV

— Tanya Harrison (@tanyaofmars) July 14, 2017

18. The south polar cap of Mars, made of CO2 ice, is mysteriously eroding away. The northern polar cap, made of water ice, seems stable. pic.twitter.com/FtrwsMLAvY

— Tanya Harrison (@tanyaofmars) July 14, 2017

Solar conjunction what’s your function? About every two years, Earth & #Mars end up on opposite sides of the sun https://t.co/Lr6MbBfkkH pic.twitter.com/21Uww7Rbc0

— NASA JPL (@NASAJPL) July 15, 2017