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Craters Timing for the Total Lunar Eclipse 3 March 2007


One of the most interesting measurements we can take during a Lunar eclipse is the careful timing of lunar craters as they enter and exit the umbra. This way we can get with precision the shape of Earth shadow, that varies from one eclipse to the next and it is related to the Earth's atmosphere.

More information can be find in this article in pdf: Size and shape of the umbra during a lunar eclipse.

The following Table lists 20 well-defined craters with predicted umbral immersion and emersion times during the lunar eclipse. Note that all predictions presented here use Danjon's rule of shadow enlargement. In particular, the diameter of the umbral shadow has been calculated assuming an enlargement of Earth's radius of 1/85 to account for the opacity of the terrestrial atmosphere. The effects of Earth's oblateness have also been included.

UT of Immersion Crater Name UT of Emersion Crater Name
21:35 Grimaldi 00:06 Grimaldi
21:37 Billy 00:06 Aristarchus
21:43 Campanus 00:13 Kepler
21:49 Kepler 00:13 Billy
21:49 Tycho 00:17 Plato
21:54 Aristarchus 00:19 Pytheas
21:57 Copernicus 00:22 Timocharis
22:02 Pytheas 00:22 Copernicus
22:08 Timocharis 00:26 Campanus
22:13 Dionysius 00:28 Aristoteles
22:13 Manilius 00:30 Eudoxus
22:17 Menelaus 00:36 Tycho
22:21 Plinius 00:37 Manilius
22:22 Goclenius 00:41 Menelaus
22:23 Plato 00:45 Dionysius
22:27 Taruntius 00:45 Plinius
22:27 Langrenus 00:56 Proclus
22:28 Eudoxus 00:59 Taruntius
22:31 Aristoteles 01:01 Goclenius
22:31 Proclus 01:07 Langrenus

Data from NASA Eclipse Home Page . Fred Espenak, NASA / GSFC

Crater timing is easy! Record the instant when the most abrupt gradient at the umbra's edge crosses the apparent centre of the crater. In the case of large craters like Tycho and Copernicus, record the times when the shadow touches the two opposite edges of the crater. The average of these times is equal to the instant of crater bisection.

You should be thoroughly familiar with these features before viewing an eclipse in order to prevent confusion and misidentification. This map, as well as the one from the document in pdf above, can be of help as a planning guide.


Names of some of the most important Moon craters.
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