17 Thetis

17 Thetis is a large main-belt asteroid that was discovered by R. Luther on April 17, 1852. It was his first asteroid discovery. The name comes from Thetis, the mother of Achilles in Greek mythology.

One Thetidian stellar occultation was observed from Oregon in 1999. However, the event was not timed.

The spectrum of this object indicates that it is an S-type asteroid with both low and high calcium forms of pyroxene on the surface, along with less than 20% olivine. The high-calcium form of pyroxene forms 40% or more of the total pyroxene present, indicating a history of igneous rock deposits. This suggests that the asteroid underwent differentiation by melting, creating a surface of basalt rock.

Mass

The mass of Thetis has been calculated from perturbations by 4 Vesta and 11 Parthenope. In 2007, Baer and Chesley calculated Thetis to have a mass of 1.2×10¹⁸ kg with a density of 3.21 g/cm³.

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Thetis

Thetis (/ˈθɛtɪs/; Greek: Θέτις [tʰétis]), is encountered in Greek mythology mostly as a sea nymph or known as the goddess of water, one of the 50 Nereids, daughters of the ancient sea god Nereus.

When described as a Nereid in Classical myths, Thetis was the daughter of Nereus and Doris, and a granddaughter of Tethys with whom she sometimes shares characteristics. Often she seems to lead the Nereids as they attend to her tasks. Sometimes she also is identified with Metis.

Some sources argue that she was one of the earliest of deities worshipped in Archaic Greece, the oral traditions and records of which are lost. Only one written record, a fragment, exists attesting to her worship and an early Alcman hymn exists that identifies Thetis as the creator of the universe. Worship of Thetis as the goddess is documented to have persisted in some regions by historical writers such as Pausanias.

In the Trojan War cycle of myth, the wedding of Thetis and the Greek hero Peleus is one of the precipitating events in the war which also lead to the birth of their child Achilles.

Thetis (island)

Thetis (Greek: Θέτις) is a small islet off the southern coast of the Greek island of Crete in the Libyan Sea. The islet is administered from Asterousia in Heraklion regional unit.

Thetis (decoy)

Thetis was the name of a floating radar decoy used by German U-boats during the Second World War.

The device was stored dismantled in the bow compartment as a pole about two metres long. Assembly usually took place in the U-boat's conning tower, and could be assembled in about four minutes (FuMT 2 - Thetis IIC). Later versions could be launched from a standard torpedo tube (FuMT 4 - Thetis US). When deployed, it was extended to a total length of eight metres, half of which was submerged. The upper half had a series of reflectors that were tuned to Allied anti-submarine radar wavelengths to give the same return signal as a U-boat. The number of Thetis decoys carried varied between different U-boats: