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52 Europa

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52 Europa
Europa as seen in 24 inch telescope
Discovered by H. Goldschmidt
Discovery time February 04, 1858
Other names 1948 LA
Group Main belt
Reference date November 26, 2005 (JD 2453700.5)
Longest distance from the Sun 511.201 Gm (3.417 AU)
Shortest distance from the Sun 416.621 Gm (2.785 AU)
Longest distance from the center of its orbital path
("semi-major axis")
463.911 Gm (3.101 AU)
How egg-shaped its orbit is
How long it takes to complete an orbit 1994.629 d (5.46 a)
Average speed 16.87 km/s
Mean anomaly 70.730°
Angle above the reference plane
Longitude of where it comes up through the reference plane 128.992°
Angle between its shortest distance from what it orbits around and where it comes up through the reference plane
("argument of periapsis")
Size and Other Qualities
Measures 360×315×240 km[1][2]
Mass 5.2±1.8×1019 kg[3]
Average density 3.6±1.2 g/cm³
Gravity at its surface ~0.11 m/s²
Slowest speed able to escape into space
("escape velocity")
~0.20 km/s
How long it takes to turn around one time 0.2347 d [4]
How much light it reflects 0.058 [1]
Avg. surface temp. ~173 K
max: 258K (-15 °C)[5]
Light-band group
("spectral type")
C-type asteroid
True brightness
("absolute magnitude")

52 Europa is an asteroid. It has a diameter of 289 km, and was found on February 4, 1858 by H. Goldschmidt. It is named after Europa, one of Zeus's conquests in Greek mythology. Europa is the seventh biggest asteroid by volume and the sixth biggest by mass (after Ceres, Vesta, Pallas, Hygiea, and Interamnia) and contains somewhat less than 2% of the mass of the entire main belt.

It is a very dark carbonaceous C-type, and the fourth-biggest of these. It orbits close to the Hygiea asteroid family, but is not a member. Spectroscopic studies have found evidence of olivines and pyroxenes on the surface.

Lightcurve data for Europa has been very hard to interpret, so much so for a long time its period of rotation was in dispute (5 and a half, or 11 hours?) despite many observations[8]. It has now been determined that Europa is a prograde rotator, but the exact direction in which its pole points remains unclear. The most detailed analysis indicates that it points either towards about ecliptic coordinates (β, λ) = (70°, 55°) or (40°, 255°) with a 10° uncertainty [2]. This gives an axial tilt of about 14° or 54°, respectively.

It has been found that the star CV Aquarii found in 1934, was actually an incorrect misidentification of 52 Europa[6].


  1. T. Michałowski et al. Photometry and models of selected main belt asteroids I. 52 Europa, 115 Thyra, and 382 Dodona, Astronomy & Astrophysics, Vol. 416, p. 353 (2004).
  2. PDS lightcurve data
  3. E. Dotto et al. ISO results on bright Main Belt asteroids: PHT – S observations, Astronomy & Astrophysics, Vol. 358, p. 1133 (2000).
  4. S.R. Sawyer A High-Resolution CCD Spectroscopic Survey of Low-Albedo Main Belt Asteroids, PhD thesis, The University of Texas (1991).
  5. P. Schmeer and M.L. Hazen CV Aquarii identified with (52) Europa, Journal of the American Association of Variable Star Observers, Vol. 28, p. 103 (2000).
  6. V. Zappalà, M. di Martino and S. Cacciatori On the ambiguity of rotational periods of asteroids - The peculiar case of 52 Europa, Icarus, Vol. 56, p. 319 (1983).

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