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Explanation: What causes the black dots on dunes on Mars? As spring dawns on the Northern Hemisphere of Mars, dunes of sand near the poles being to defrost. Thinner regions of ice typically thaw first revealing sand whose darkness soaks in sunlight and accelerates the thaw. By summer, the spots will have expanded to encompass the entire dunes that will then be completely thawed and dark. The carbon dioxide and water ice actually sublimes in the thin atmosphere directly to gas. Taken in mid-July, the above image shows a field of spotted polar dunes spanning about 3 kilometers near the Martian North Pole. Meanwhile, in the Southern Hemisphere of Mars, the Earth-sent robot Martian rovers will try to survive through Martian winter, which peaks in mid-September.
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NASA Web Site Statements, Warnings, and Disclaimers
NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: Mars - sand
Publications with words: Mars - sand
See also:
- APOD: 2025 July 15 B Collapse in Hebes Chasma on Mars
- APOD: 2025 July 6 B The Spiral North Pole of Mars
- APOD: 2025 June 29 B Dark Sand Cascades on Mars
- APOD: 2025 June 22 B A Berry Bowl of Martian Spherules
- APOD: 2025 June 15 B Two Worlds One Sun
- Perseverance Selfie with Ingenuity
- Deimos Before Sunrise