THE SOUTHWORTH PLANETARIUM
70 Falmouth Street      Portland, Maine 04103
(207) 780-4249      usm.maine.edu/planet
43.6667° N    70.2667° W  Altitude:  10 feet below sea level Founded
January 1970
2021-2022: LXXX
"In nature nothing is perfect and everything is perfect. Trees can be
contorted, bent in weird ways, and they're still beautiful." -Alice Walker

THE DAILY ASTRONOMER Wednesday, February 9, 2022
Quadruple Asteroid

Today's excursion into the wild and unbounded black yonder takes us into
the asteroid belt, where one would find thousands upon thousands of these
oddly shaped rocky bodies careening through the gulfs of interplanetary
space. Our destination however is one asteroid, or, more correctly, a
system of four asteroids: the first quadruple asteroid system to be
discovered.

Vacillating between 3.7 and 2.4 AU* from the Sun, 130 Elektra is a
carbonaceous asteroid approximately 200 kilometers in diameter. Discovered
in 1873 -hence the comparatively low designation number- by German-American
astronomer Christian Heinrich Friedruch Peters (1813-1890), Elektra has
been known to possess two moons. The first moon was discovered in 2003; the
second in 2014. Now, an astronomical team led by the National Astronomical
Research Institute of Thailand's Anthony Berdeu has examined images of
Elektra captured by the Very Large Telescope in Chile. They've recently
announced the discovery of a small third moon moving within the orbits of
the two previously discovered moons. This new moon measures merely 1 mile
in diameter, smaller than its two companion moons (1.2 and 3.7 mile
diameters).   As its mean distance from Elektra is only 220 miles, this
meager little moon completes an orbit around its parent body every 16
hours!


[image:
merlin_201573207_8fb78450-bfa9-4e8e-a266-523e4bf4a158-superJumbo.jpg]
Images of Electra and two of its three "moons" captured by the European
Southern Observatory's Very Large Telescope.

Observations show that the compositions of the moons and Elektra are
similar, suggesting that the satellites are fragments of Elektra dislodged
by a collision that occurred at an indeterminate time.      In fact, the
small moon just discovered is so close to the main asteroid that it might
eventually fall back onto it.

For now, astronomers are excited at the discovery of the first known
quadruple asteroid system.   They are hopeful that the new algorithms that
enabled the VLT astronomers to find Elektra's third moon will help them to
find other such quadruples -and perhaps even quintuples- in the near future.

*AU = astronomical unit, equal to Earth's mean distance from the Sun or
approximately 93 million miles.


To subscribe or unsubscribe from the Daily Astronomer:
https://lists.maine.edu/cgi-bin/wa?SUBED1=DAILY-ASTRONOMER&A=1