Isis,

minor planet designation A formal minor-planet designation is, in its final form, a number–name combination given to a minor planet (asteroid, centaur, trans-Neptunian object and dwarf planet but not comet). Such designation always features a leading number (catalog or ...

: 42 Isis, is a large

main-belt The asteroid belt is a torus-shaped region in the Solar System, located roughly between the orbits of the planets Jupiter and Mars. It contains a great many solid, irregularly shaped bodies, of many sizes, but much smaller than planets, called ...

asteroid An asteroid is a minor planet of the inner Solar System. Sizes and shapes of asteroids vary significantly, ranging from 1-meter rocks to a dwarf planet almost 1000 km in diameter; they are rocky, metallic or icy bodies with no atmosphere. ...

, measuring 100.2 km in

diameter In geometry, a diameter of a circle is any straight line segment that passes through the center of the circle and whose endpoints lie on the circle. It can also be defined as the longest chord of the circle. Both definitions are also valid for ...

with a stony ( S-type) composition. It was discovered by English astronomer N.R. Pogson on 23 May 1856 at

Oxford Oxford () is a city in England. It is the county town and only city of Oxfordshire. In 2020, its population was estimated at 151,584. It is north-west of London, south-east of Birmingham and north-east of Bristol. The city is home to the ...

, and was his first asteroid discovery. The asteroid's name was chosen by

Manuel John Johnson Manuel John Johnson, FRS (23 May 1805 – 28 February 1859) was a British astronomer. He was born in Macao, China, the son of John William Roberts of the East India Company and was educated at Mr Styles' Classical Academy in Thames Ditton and at ...

, director of the

Radcliffe Observatory Radcliffe Observatory was the astronomical observatory of the University of Oxford from 1773 until 1934, when the Radcliffe Trustees sold it and built a new observatory in Pretoria, South Africa. It is a Grade I listed building. Today, the obse ...

in Oxford. Although

Isis Isis (; ''Ēse''; ; Meroitic: ''Wos'' 'a''or ''Wusa''; Phoenician: 𐤀𐤎, romanized: ʾs) was a major goddess in ancient Egyptian religion whose worship spread throughout the Greco-Roman world. Isis was first mentioned in the Old Kingd ...

is the name of an

Egyptian goddess Ancient Egyptian deities are the gods and goddesses worshipped in ancient Egypt. The beliefs and rituals surrounding these gods formed the core of ancient Egyptian religion, which emerged sometime in prehistory. Deities represented natural fo ...

, the name was chosen in homage to Pogson's astronomer daughter, (Elizabeth)

Isis Pogson Isis Pogson, (born Elizabeth Isis Pogson; 28 September 1852 – 14 May 1945), was a British astronomer and meteorologist, who was one of the first women to be elected as a fellow of the Royal Astronomical Society. Biography Early life Pogson ...

. In addition,

the Isis "The Isis" () is an alternative name for the River Thames, used from its source in the Cotswolds until it is joined by the Thame at Dorchester in Oxfordshire. It derives from the ancient name for the Thames, ''Tamesis'', which in the Middle ...

is the stretch of the River Thames that runs through Oxford. This asteroid is orbiting the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

with a period of 3.82 years. The

light curve In astronomy, a light curve is a graph of light intensity of a celestial object or region as a function of time, typically with the magnitude of light received on the y axis and with time on the x axis. The light is usually in a particular frequ ...

inversion technique, when applied to photometric observations of this asteroid, show multiple local irregularities. The overall shape displays little elongation, with a ratio between the major and minor axes equal to 1.1. The measured rotation period for this model is 13.6 hours. The spectrum of 42 Isis reveals the strong presence of the mineral

Olivine The mineral olivine () is a magnesium iron silicate with the chemical formula . It is a type of nesosilicate or orthosilicate. The primary component of the Earth's upper mantle, it is a common mineral in Earth's subsurface, but weathers quickl ...

, a relative rarity in the asteroid belt.

References

External links

* * {{DEFAULTSORT:000042 S-type asteroids (Tholen) L-type asteroids (SMASS) Background asteroids

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