Pluto
17.2°Earth
0.0°Mercury- 0 °
Venus
3.4°Mars
1.9°Jupiter
1.3°Saturn
2.5°Uranus
0.8°Neptune
1.8°Spin axisASTRONOMY: ROEN KELLYWWW.ASTRONOMY.COM 13
The spiral galaxy UGC 2885,
also called Rubin’s Galaxy, is
something of a local legend. At
232 million light-years away, it
is the largest galaxy known in
our nearby universe, spanning
more than twice the width of
the Milky Way and containing
10 times as many stars. But
astronomers aren’t sure how it
got so large. Galaxies typically
grow by consuming or smash-
ing into other galaxies. But
UGC 2885 is alone in space,
apparently having undergone
neither process to gain its heft.
Instead, researchers believe
it may have grown by calmly
siphoning gas from intergalac-
tic space. One way to read the
galaxy’s past is to study the globular clusters of stars around
it. These clusters often survive collisions and assimilations,
revolving around the final result. Astronomers are now look-
ing to count up the globular clusters around UGC 2885 to
see whether it has more than it should, which would hint
that it’s eaten other galaxies in the past. — A.K.
Our nearby
gentle giant
TILT-A-WHIRL. The planets orbit our Sun in a relatively f lat plane. But the key word here is relatively —
some planets lie closer to this plane than others. The amount a planet’s orbit is tilted, or inclined, away
from the plane is called its inclination. As earthbound observers, we have defined the plane of the
solar system, called the ecliptic, as the orbit of Earth around the Sun. Therefore, Earth has
an inclination of 0.0°. Here’s how the other planets (and Pluto) stack up. — A.K.HOW THE PLANETS LINE UP
FAST FACT
The planets orbit in a plane because
the solar system formed out of a
relatively flat disk of gas and dust
swirling around our infant Sun.NASA, ESA, AND B. HOLWERDA (UNIVERSITY OF LOUISVILLE)$58,
The total, in USD, awarded
by the Planetary Society, in
varying amounts, to six amateur astronomers
focused on discovering and characterizing
near-Earth asteroids.