Interesting video on Weather Channel’s website that shows an aerial image of a 1/2 mile tall, 100 foot wide dust devil sweeping the sandy martian plains. The resolution of the satellite image is pretty amazing, and allows researchers the ability to calculate the twister’s dimensions based on the length of the shadow it cast (and knowing the angle of the sun at the moment the shot was taken.)
Martian dust devils aren’t a new discovery — we’ve known about them for quite some time, and even have recorded images of them from the surface of the planet. One fascinating and unexpected element they’ve added to human exploration of that planet is periodically cleaning the dust from the solar panels of the martian rovers we’ve sent there.
If you want to find the height of a tall object on Earth and can measure the length of its shadow (easier around noon than in the early morning or late afternoon, when shadows stretch pretty long), you can use this height-by-shadow-length calculator to get the result (clicking the image will take you to the calculator page).