Astronomy Terms For Beginners For Beginners

If you are starting out with a telescope or a set of binoculars for astronomy, and are interested in finding your way around the night sky you might come across terms used in astronomy you’ve never heard before. So, we’ve compiled the following astronomy terms and definitions to help .

What This Covers

What is Astronomy?

Astronomy is “the scientific study of all objects in space” ¹ or otherwise stated as “the study of celestial objects and phenomena” ².

Astronomy For Beginners - cool space terms

The following list of words* are associated with space and the Universe.

You’ll find these ‘words to do with space’ listed in alphabetical order and their meanings provided alongside.

A
Aberration of starlight	Change appearing in the star's position
Aphelion	An object is at its fartherest from the sun at this point
Apogee	An orbiting star is at its fartherest from the sun at this point
Armillary sphere	A model of objects in the sky designed in a spherical framework of rings to show the relationships between them on the celestial sphere
Asteroid	A minor planet that orbits around the Sun and which no more than 600 miles (1000 kms) in diameter.
Azimuth	The horizontal bearing of a celestial object. It is measured clockwise from a given direction.
B
Binary star	Two stars connected through gravitational attraction.
Black hole	In space, an area where gravitational pull is so strong that not even light can escape it.
C
Celestial sphere	The sphere around the Earth that is imagined for the purpose of finding or identifying the position of clestial bodies
Conjunction	The occasion when two celestial bodies align on the celestial sphere
Corona	The faint light seen as a halo around the Sun and Moon
Cosmology	The study of the cosmos - deals with the origin and evolution of the Universe. A branch of astronomy.
D
Declination	Angular measure of a star's position in degrees north and south of the celestial equator
Double star	See binary star
E
Ecliptic	A circle representing the annual path of the Sun apparent on the celestial sphere in relation to other stars
M
Magnitude	A celestial body's brightness as a measure, apparent or absolute.
Meteorite	A rock or metal chunk from space of a size that can pass through the atmosphere to reach the Earth's surface without burning up.
N
Nadir	The point in the sky directly under the observer or diametrically opposite the Zenith
Nebula	A galaxy dust or gas cloud
Notation	When a slight "nodding" of the Earth's axis occurs
Nova	A star that brightens suddenly to several times its normal magnitude of brightness.
O
Open star cluster	A group of up to a few thousands of stars loosely bound by gravitational attraction and formed from the same giant molecular cloud.
Perihelion	An object in orbit of the Sun is closest to the Sun at this point
P
Perigee	An orbiting object is closest to Earth at this point.
Perihelion	An object in orbit of the Sun is closest to the Sun at this point
Pulsar	A star that rotates rapidly and transmits a regular radiation flash
Q
Qasar	Object of intense brightness, possibly an energetic nucleus of a far off galaxy.
R
Red shift	Lengthening of the light wavelength from a receding celestial body.
S
Singularity	There is an infinity density of matter at this point in space-time.
Solstice	The fartherest point either north or south of the equator that the Sun reaches each year.
Super nova	An end of life star exploding.
Syzygy	A celestial body is either in opposition to or in conjuction with the Sun at this point in its orbit.
Z
Zenith	The point in the sky that is directly above the observer.

*Sources: Reader’s Digest 1989, ‘Astronomy Terms’ in Reverse Dictionary Reader’s Digest Association Ltd.

Branches of Astronomy

In our list of outer space terms we included one branch of astronomy – Cosmology.

If you are interested in a career in astronomy you might want to consider one of the following 17 branches that fall into four subfields: Astrophysics, Astrometry, Astrogeology, and Astrobiology. ²

ASTROPHYSICS
Astrophysics	The study of the laws of physics as it applies to stars and celestial bodies.
Cosmology	The study of the origin and evolution of the universe.
Spectroscopy	The study of light reflection, absorption, and transfer between matter.
Photometry	The study of luminous astronomical objects in relation to electromagnetic radiation
Asteroseimology	The study of internal struction of stars through observing their oscillations.
Helioseismology	The study of the composition of stars in terms of their interior structure and dynamics by way of observing their surface waves
Solar Physics	The study of the laws of physics as it applies to the Sun.
Heliophysics	The study of the Sun's constant and dynamic radiation effect on its surrounds in space.
ASTROMETRY
Astrometry	The study of celestial bodies in terms of their position and how they move in space.
Planetology	The study of planets in terms of how they form, including their composition and dynamics in history.
Exoplanetology	The study of planets that exist outside our solar system.
ASTROGEOLOGY
Areology	The study of the geological composition of Mars.
Selenography	The study of the Moon's physical features, e.g. the luna maria, craters, and mountain ranges.
Exogeology	The study of geology relating to moons, asteroids, meteorites, comets, and other celestial bodies. (also known as Planetary Geology)
ASTROBIOLOGY The study of the origin and evolution of life in the Universe.
Exobiology	The study of the likelihood of life in space.
Astroecology	The study of the interactions of biota with space environments.
Astrochemistry	The study of chemical substances in celestial bodies, stars and interstellar space