All About Space - UK (2020-02)

Conjunction

A conjunction is an alignment of objects at the same

celestial longitude. The conjunction of the Moon and

the planets is determined with reference to the Sun.

A planet is in conjunction with the Sun when it and

Earth are aligned on opposite sides of the Sun.

Opposition

When a celestial body is in line with the Earth and

Sun. During opposition, an object is visible for the

whole night, rising at sunset and setting at sunrise. At

this point in its orbit, the celestial object is closest to

Earth, making it appear bigger and brighter.

Declination (Dec)

This tells you how high an object will rise in the sky.

Like Earth’s latitude, Dec measures north and south.

It’s measured in degrees, arcminutes and arcseconds.

There are 60 arcseconds in an arcminute and there

are 60 arcminutes in a degree.

Magnitude

An object’s magnitude tells you how bright it

appears from Earth. In astronomy, magnitudes are

represented on a numbered scale. The lower the

number, the brighter the object. So, a magnitude of

-1 is brighter than an object with a magnitude of +2.

Right Ascension (RA)

Right Ascension is to the sky what longitude is to

the surface of the Earth, corresponding to east and

west directions. It is measured in hours, minutes and

seconds since, as the Earth rotates on its axis, we see

different parts of the sky throughout the night.

Greatest elongation

When the inner planets, Mercury and Venus, are at

their maximum distance from the Sun. During greatest

elongation, the inner planets can be observed as

evening stars at greatest eastern elongations and as

morning stars during western elongations.

Jargon buster

Conjunction between

Venus and Uranus

in Aries

9

MAR

The Moon and Mars

make a close approach,

passing within 1°23’ of

each other in Cancer

6

MAR

Mercury reaches its

highest point in the

morning sky, shining

brightly at +0.2

13

MAR

Conjunction of the

Moon and Jupiter,

passing within 1°30’ of

each other in Sagittarius

18

MAR

The Moon, Mars and

Jupiter make a close

approach in Sagittarius

18

MAR

Conjunction between

the Moon and Saturn

in Sagittarius

18

MAR

Conjunction between

Jupiter and Mars

in Sagittarius

20

MAR

Jupiter and Mars make a

close approach, passing

within 0°42’ of each

other in Sagittarius

20

MAR

March Equinox

20

MAR

Mercury reaches its

greatest elongation in

the dawn sky, shining

brightly at +0.2

23

MAR

Venus reaches its

greatest elongation in

the evening sky, shining

brightly at -4.4

24

MAR

Naked eye

Binoculars

Small telescope

Medium telescope

Large telescope

STARGAZER

What’s in the sky?

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