These days, longitude on Mars is measured even more precisely using radio tracking of landers such as InSight, however everything is still specified to keep no longitude focused on this crater.
The full view image shows more of the surrounds of the Airy-0 crater on Mars. Credit: NASA/JPL-Caltech/UArizona
This image was caught by the High-Resolution Imaging Science Experiment (HiRISE), on the Mars Reconnaissance Orbiter. The map is predicted here at a scale of 50 centimeters (19.7 inches) per pixel.
For more recent picture of spectacular craters on Mars, see Martian Brain Freeze: Mars Express Reveals Utopia Planitia.
The crater in the center of this HiRISE image defines where zero longitude is on Mars, like the Greenwich Observatory does for the Earth. Credit: NASA/JPL-Caltech/UArizona
Although the image above isnt brand-new (it was captured by the High-Resolution Imaging Science Experiment (HiRISE), on the Mars Reconnaissance Orbiter on September 8, 2021), NASA just posted it to Instagram today. The sensational image went viral, with some saying that it appeared like an alien footprint.
Youre taking a look at 0 ° longitude on Mars– the Greenwich Observatory equivalent on the Red Planet. The Greenwich Observatory marks Earths Prime Meridian, which is a north-south line that specifies where east meets west, and is used as the zero-reference line for huge observations.
Zooming out a bit, we see the Airy-0 crater is a broader context. Credit: NASA/JPL-Caltech/UArizona
The bigger crater that sits within this crater, called the Airy Crater, originally defined zero longitude for Mars, however as greater resolution pictures ended up being readily available, a smaller feature was needed. This crater, called Airy-0 (no) was chosen due to the fact that it did not need to change existing maps.