Iphigenia.space

Main-belt asteroid (dark, carbonaceous) · Inner main belt · ≈ 2.43 AU

Iphigenia

(112) Iphigenia · discovered 1870 by C. H. F. Peters

An exceptionally dark, slowly turning asteroid found by its discoverer on his own birthday.

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Iphigenia at a glance
Object typeMain-belt asteroid; C-type, primitive carbonaceous (SBDB: Tholen DCX, SMASS Ch)[1]
DiscoveredSept. 19, 1870 by C. H. F. Peters, Litchfield Observatory, Clinton, NY[2]
Named forIphigenia, a princess of Greek myth[2]
Diameter≈ 70 km[1]
Geometric albedo≈ 0.042 — very dark[1]
Rotation period≈ 31.4–31.5 hours[1]
Light-curve amplitude≈ 0.30 magnitude[2]
Distance from Sun2.12–2.74 AU[1]
Orbital period≈ 3.8 years[1]
Inclination≈ 2.6°[1]
First orbit published1871, by Friedrich Tietjen[2]

One of the darker large asteroids

Iphigenia is described as fairly large and exceedingly dark.[2] JPL lists a diameter of about 70 km and a geometric albedo of just 0.042: it reflects only about 4% of the light that hits it.[1]

It is classed as a C-type asteroid, so it probably has a primitive carbon-rich composition.[2]

A birthday discovery

Iphigenia was discovered on 19 September 1870 by C. H. F. Peters at Hamilton College in Clinton, New York.[2] Peters was born on 19 September 1813, so he found it on his 57th birthday.[3]

The German astronomer Friedrich Tietjen published its orbital elements the following year.[2]

The name

The asteroid is named after Iphigenia, a princess in Greek mythology who was sacrificed by her father.[2] Like many early asteroids, it took its name from classical myth.

A slow turner

Photometry from the Observatorio Astronómico de Mallorca in 2007 gave a rotation period of 31.385 ± 0.006 hours, with brightness changing by about 0.30 magnitude per cycle. An independent 2008 result gave 31.466 hours.[2] That is slow compared with the few-hour spins of many asteroids of its size.

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Orbit

Iphigenia orbits in the inner main belt, between 2.12 and 2.74 AU from the Sun, once every 3.8 years, on an orbit tilted only 2.6°.[1]

Sun Earth (1 AU)Mars (1.52 AU) aphelion ≈ 2.74 AU perihelion ≈ 2.12 AU
Top-down orbit of Iphigenia to scale, computed from JPL orbital elements (a ≈ 2.43 AU, e ≈ 0.128).[1] Earth and Mars orbits shown for comparison.[5]

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C. H. F. Peters: revolutionary, surveyor and asteroid hunter

The life of the German-American astronomer who found Iphigenia and 47 other asteroids from upstate New York.

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Why is Iphigenia so dark?

An albedo of 0.042, a carbonaceous classification, and what dark asteroids tell us about the early Solar System.

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Measuring a 31-hour spin

How observers in Mallorca and elsewhere timed one of Iphigenia’s slow rotations.

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Sources

  1. Small-Body Database Lookup: 112 Iphigenia — NASA JPL Solar System Dynamics
  2. 112 Iphigenia — Wikipedia
  3. Christian Heinrich Friedrich Peters — Wikipedia
  4. Light curve — Wikipedia
  5. Planetary Fact Sheet (orbit comparison) — NASA NSSDCA

Figures are rounded; where sources differ we note it. Spotted an error? Tell us.