Professor of Mathematics

Paata Ivanisvili

Department of Mathematics, University of California, Irvine

Candidate 31: Plains west of Uranius Mons

Strong · roughly 90%

Two CTX close-ups of the same 500 by 500 m of plains west of Uranius Mons, from May 2016 and December 2024, under a similar sun. A small, very dark spot at the arrow is present only in the 2024 image. — The same 500 × 500 m in May 2016 and December 2024, under a similar sun. The arrow marks the new spot. NASA/JPL-Caltech/MSSS.

What changed. A compact, very dark spot about 35 by 30 m appeared on the plains west of the volcano Uranius Mons between May 2016 and August 2020. It is still there in December 2024 and February 2025, on three orbits in all.

Why it may be a new impact. Images from 2014 and 2016 show nothing there, and both would have shown it. On these bland, flat plains there is nothing to cast a shadow, and a compact spot unchanged for four and a half years, in images taken under different suns, is the typical mark of a small impact.

Location: 26.333° N, 264.720° E (95.280° W)
Absent: 9 August 2014 and 12 May 2016
Present: 12 August 2020, 5 December 2024 and 10 February 2025
Size: Compact, very dark spot about 35 × 30 m
Confidence: Strong candidate; roughly 90% that it is a new impact.
Caveat: It first shows in a 2020 image, so the camera teams may already have it on their unpublished lists; but it lies outside every footprint of the high-resolution HiRISE camera, and the teams normally photograph a new impact with HiRISE within months of noticing it. Like every candidate here, it is unconfirmed: see the caveat.

Five CTX images of the same 2 by 2 km patch of plains, from 2014 to 2025. A small, very dark spot at the arrow is absent in 2014 and 2016 and present from 2020 on. — All five CTX images of the same 2 × 2 km patch, 2014 to 2025. NASA/JPL-Caltech/MSSS.

A 12 by 12 km CTX view from February 2025 of the plains around the spot, with a dashed box around the 2 by 2 km patch and an arrow at the spot. — A 12 × 12 km view from February 2025. The dashed box is the 2 × 2 km patch. NASA/JPL-Caltech/MSSS.

The independent check: three columns of the same ground, 2 km wide above and 600 m wide below, with yellow ticks around the spot. The spot is missing in the earlier image, marked BEFORE, and present in the two later images, marked AFTER. — **Independent check.** A second, deliberately sceptical review downloaded every image again and found that the candidate passes every test. Each column is the same ground, north up, 2 km wide above and 600 m wide below. Columns marked BEFORE are earlier images in which the spot would have been visible had it been there; those marked AFTER show it. Each image keeps one contrast stretch in both rows, so the close-up cannot create a spot. NASA/JPL-Caltech/MSSS.