Herodotus Omega

In Oceanus Procellarum in between Marius and Herodotus craters lies Herodotus Omega volcanic dome. This region contains a number of volcanic features, such as sinuous rilles and the Marius hills volcanic domes further south. Herodotus Omega is an impressive mound with a 3.5 km long crater or collapsed lava tube on the summit. With the Sun high overhead, however, it’s easy to overlook it.

High sun

Lat: 20.8   Lon: -50.0
Forum regular JFincannon has a knack of finding interesting images and came across the above feature while browsing a Wide Angle Camera (WAC) image of a region around Aristarchus. He then persevered to find the same region imaged under a lower Sun. It was well worth it to see the dome and a nearby rille pop out into view.

Low sun

It is described as a “Platykurtic oblong mare dome with trench-like crater or collapsed lava tube on summit.” in the GLR Catalog of Lunar Domes and also appears in an unofficial Brungart catalogue identified by LPOD creator Chuck Wood.

This is a cross-section from the Quick Map tool showing the shape and height of the mound and depth of the central depression.

Though striking in LRO images there are many volcanic domes in this region and this is just one more so perhaps not surprisingly a search of the literature revealed no recent papers referencing Herodotus Omega. JFincannon found these papers from over 30 years ago. Herodotus Omega warrants only the briefest of mentions:

So it’s overdue some time in the limelight. You can explore further via the Narrow Angle Camera (NAC) images: M137875459RE, M116642442RE and the ACT-REACT Quick Map.  To fully appreciate the dome you really need to explore the wide-field WAC images. This is how JFincannon did it:

1. He searched for low Sun angle WAC images of Aristarchus (incidence angle of 70-90 degrees) using the WMS browser.
2. Then he used Mosher’s LROC WAC Previewer.
3. Full instructions are here.

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About juleswilkinson

Citizen scientist and volunteer. Forum moderator for the Milky Way Project, Solar Stormwatch, Science Gossip and Shakespeare's World. Owner of 3 telescopes, a dog and a meteorite.

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