Celestial observation flash cards

Constellation def (Question)

A group of stars forming a recognizable pattern (Anwser)

Asterism def (Question)

A prominent group of stars that is not a constellation (Answer)

How many constellations are there (Question)

88 (Answer)

How many stars are in Cassiopeia (Question)

5 (Answer)

How do you find the star ‘Sirius’ from Orion (Question)

The three stars in Orions belt points down to Sirius

What two stars are used to find Polaris in the plough

Dubhe and Merak

How do you find Polaris using the plough?

Draw a line from Merak to dubhe and follow it to usra minor and Polaris

What is right accession measured in?

Hours, minutes, seconds

What is right ascension?

Right ascension is the longitude on the celestial sphere, its the distance of a point east from the point of aries

How long is a ‘sidereal day’

23h 56m long

What is declination? 

Declination is the latitude of a star in the sky measured from the Celestial Equator.

What is altitude?

How high a star is from the horizon (0 degrees) to the zenith of the observer (90 degrees)

What is azimuth?

The direction of the star from the observer, measured from North (0 degrees) eastward 

How do you work out a stars declination from the observers latitude and where it culminates?

90 – Latitude = x
Where it culminates - x = Declination

e.g

A star seen from London (51°) culminates at 30° above the horizon

90 – 51 = 39
30-39= 9° N Declination

What is an circumpolar star?

A star that never goes below the horizion

How do you work out the magnification of a telescope?

Focal length of the objective lens / focal length of the eyepiece