SEEING DOUBLEby Jeff Hecht
34 FEBRUARY 2020 • SKY & TELESCOPE
Binary
Worlds
PRIMITIVE WORLDThe Kuiper
Belt object 2014 MU 69 (now offi cially
named Arrokoth) is a contact binary,
each lobe a hodgepodge of smaller
regions. Scientists think this is the
most unchanged object from the
solar system’s formation that a
spacecraft has so far encountered.
Mercury Venus Earth Mars Asteroid belt Jupiter
127
near-Earth asteroids
(55 are contact
binaries)
28
Mars
crossing
asteroids
180
main-belt
asteroids
(1 co-classified
as a comet,
11 are contact
binaries)
3
Jupiter Trojan
asteroids (at L 4 )
(1 is a contact binary)
4
Jupiter Trojan
asteroids (at L 5 )
(1 is a contact binary)
1
contact binary
inside Earth’s orbit
6
contact binary
comets
NOT TO SCALE