First published in November 2014

Word Definition
almagestA textbook or handbook, esp dealing with astronomy.
ansaPart of Saturn's rings.
aphelionThe point when the earth is farthest from the sun during its annual orbit
apogeeThe point in the orbit of a body revolving round the earth that is farthest from the centre of the moon.
apoluneThe point in the orbit of a body revolving round the moon that is farthest from the centre of the moon.
areologyThe study of Mars.
azimuthThe angle a celestial object makes from due north, when measured in an eastwards direction along the horizon.
blazarA type of active galaxy that is a more energetic source of radiation than a quasar.
bolideA large meteor that bursts; a fireball.
cepheidA star of a type having regular cycles of brightness which can be used to deduce their distances.
colureA celestial circle that intersects another at the poles.
coudeDesignating a reflecting telescope in which one or more plane mirrors reflects the light down the polar axis.
daysideThe side of a planet facing the sun.
daystarThe planet Venus.
deorbitTo come out of an orbit.
earthsetThe setting of the earth as seen from the moon.
equantA term in Ptolemy's astronomical system.
faculaAn unusually bright spot on the sun's surface.
geoprobeA space probe for exploring space near the earth.
lunanautOne who travels to the moon.
magnetarA type of neutron star that has a very intense magnetic field.
masconA concentration of dense mass beneath the moon's surface.
moonletA small moon.
moonsetThe setting of the moon.
plerionA supernova remnant emitting radiation from both centre and shell.
satellesAn obsolete word for a satellite.
siderealOf or relating to the stars; measured by apparent motion of the stars.
spinarA rapidly spinning galactic body.
thindownA lessening in the number of atomic particles and cosmic rays passing through the earth's atmosphere.
ursidA meteor.