Topic 6 Flashcards
(23 cards)
what can be found from orion’s belt asterism
sirius (bottom left)
up to right:
aldebaran
pleides
underneath:
orion nebula
how can u find the winter triangle asterism in night sky
use orions belt to find sirius which is at bottom of triangle
orion’s shoulder is top right point of triangle
what is the pleides
an open cluster
define binary stars
stars that orbit around a common centre of orbit
state 2 types of cluter
open cluster
globular cluster
what do globular clusters look like
spherical shaped with more stars nearer nucleus
(resembles a fuzzy ball)
what do aurora look like
moving curtains of coloured light
what stars can be found with the plough (asterism of ursa major)
arcturus (follow the arc)
polaris (use right side pointing up)
what can be found using the great square of pegasus
right side points down:
to fomalhaut
top line points left (slightly up):
to andromeda galaxy
state 5 factors affecting visibility
-light pollution
-atmospheric conditions
-observer’s location
-time of observation
-solar activity
what 2 things can solar activity cause that will affect visibility
solar flares, solar cycle
what 3 atmospheric conditions greatly affect visibility of celestial objects
weather factors like cloud coger, fog which can scatter light
atmospheric turbulence causes stellar scintillation (twinkling)
humidity and temperature - higher temp/humidity=air becomes hazy and scatters more light
define culmination
when object reaches its highest point in sky
define cicumpolarity
stars/constellations that never rise/set and so never go below the horizon so are always visible
(as they are close in proximity to one of celestial poles)
what is RA measured in
hours, minutes, seconds
describe sunspots (p1)
temporry phenomena on sun’s photosphere that appear as dark spots compared to surrounding regions
hour angle=?
local sidereal time- right ascension
elevation at celestial meridian=?
given observer’s latitude and declination of star
90+latitude-declination
OR
90-latitude+declination
(whatever is under 90 degrees)
eot=
ast-mst
how to calculate local sidereal time
angle between observer and first point of aries expressed as a time
what is hour angle
time since celestial body passsed celestial meridian
angle between observer’s meridian and celestial meridian clockwise
is right ascension measured clockwise or anticlockwise
anticlockwise
is hour angle measured clockwise or anticlockwise
clockwise
