Topic 6 - Celestial observation Flashcards
What is a meridian
An imaginary line between north and south poles through observers position
Local noon is the same as
LST
What is an hour angle
The angle between the meridian of observer and the meridian line which the star is on
What is hour angle measured in
Hours minutes seconds
What is the equation for hour angle
LST - right ascension of star
What does the Milky Way look like to the naked eye
A furry light irregular column in the sky
What can you use the be able to see stars in the Milky Way
Telescope or binoculars
What is is the group of galaxies called with the Milky Way
The local group
What does 24 hours measure in arc mins
360°
How many arc mins in 1 hour
15°
What way is the earth moving
West to east(anti-clockwise)
What way do you see objects in the sky go
East to west
What is cardinal points
The same as compass points
What does circumpolar mean
When a star never sets below the observers horizon
What is culmination
Is when a star reaches the observers meridian
What is upper culmination/transit
The highest point a star crosses the observers meridian
What is lower culmination/transit
The lowest point a star crosses the observers meridian
What is the equation for co-declination
90°-dec
What is the zenith
The point directly above observers head
Where is the zenith located
90° perpendicular to the ground
What does the altitude of the NCP equal
The observers latitude
What are the 2 equation for declination of a star
90° - latitude of observer or observers latitude + co dec of star
What is the equation for polar distance
90-dec
How long does it take for eyes to become used to and adjust to the dark
7-30 mins
What’s a light source that can be used that doesn’t ruin dark adaption
Red light
What is averted vision
When you look to an area near a faint object to be able to view it
What happens when you look at a faint object in the sky
It can look like it disappeared
Why does it look like a faint object in the sky has disappeared when you look directly at it
Because the centre part of the inside of the eye contains rods which help us distinguish bright light and colour. Areas around the forvea are cone cells which are more sensitive to faint light making it easier to see faint details
Why does relaxing your eyes help view the night sky
By straining or squinting eyes in places stress on them which makes it harder to refocus by relaxing your eyes we can improve our vision
What are binary stars/double stars
The consist of two or more stars that share a gravitational bond
Are planets brighter or dimmer than stars
Brighter
What is a constellation
A group of stars that appear to make a pattern in the sky
Can we see different constellations and asterisms at different times if the year and why
Yes due to the rotation of the earth and the tilt of our axis
What is an asterism
Is a pattern of stars that may or may not be linked to a constellation
What do comets look like form earth
Vast trails of ice and dust over a large portion of the sky thinning to a dense core
What do meteors look like from earth
Are short lived but very bright streaks of light that move across the sky in a matter of s3cinds
Who made list of constellation we use today
Ptolemy
What are constellations mainly based on
Mythology
How many constellations are there
88
Why do different countries have different names for the constellations
Different cultured beliefs and religion
What does a nebulae look like with the naked eye
A blurry patch of light in space that are in our galaxy
How long can a supernova be visible for
Up to years
What is a supernova
Is when a star dies and causes an explosion
Why does the aurora happen
Solar wind reacts with atmosphere to create spectacular displays of light and colour in sky
What is the aurorae called in the northern hemisphere
Aurorae borealis
What is the aurorae called in the Southern Hemisphere
Aurorae australis
What do artificial satellites look like to the naked eye
Slow moving faint objects orbiting in a polar orbit and viewable on the meridian
What is an open cluster
Are groups of stars close to each other in space
How many stars can be in an open cluster and where are they usually found
12-thousands of stars and found on the galactic plane
What do open clusters look like to the naked eye
Irregular shape and bright (young stars)
What do globular clusters look like
A fuzzy ball
What types of stars are found in a globular cluster
Red giants and white dwarfs
How many stars are found in a globular cluster
100000-over a million
What do aircraft look like to the naked eye
Multiple bright white and red lights slowly moving across the sky
Where are star maps and charts published
In books newspapers and magazines
Why do we use star mops and charts
To show us what is in the night sky during a month or season
How many stars maps and charts and what do they show
2 one shows west-east towards the south and the other west-east towards the north
Why is planisphere good
It’s a quick and easy way to find out what stars are viewable at any time
What is a planisphere
It consisted of two discs fastened to each other . On one of them there is a hole so that a portion of the disc underneath can be seen. around edge are hours of day and have days of the year. On the underneath disc is a star map showing very constellation a bike for viewing from a general location
What are the advantages of using software to help view the night sky
Can show sky at any given time and can offer features like 30 maps of planets or the ability to change time and location
What are the advantages of apps
Can be downloaded on different toes of phones
Most are free
What is a features in apps
Being able to point your device at the sky and identify planets and constellations
What is the horizontal coordinate system attitude
Measures how high something is in the sky from 0° at the horizon to 90° at the zenith
What is azimuth
Measure direction along horizon north = 0° travel eastward
Why does the sky appear redder at sun set and sun rise
Caused my the angle of the sun being acute so sunlight has to travel further through earths atmosphere
What is are 2 examples of a seeing condition and how does it obscure
Saharan dust or volcanic ash in the upper earth atmosphere can obscure viewing by refracting light
What is declination
Is the latitude of a star in the sky measured from the celestial equator
What is dec measured in
Degrees° arc minutes’ arc seconds “
What is right ascension
Equivalent to longitude in space
What do you use to measure right ascension
First point of aries
What is right ascension measured in
Hours h, minutes m and seconds s
What time of weather conditions can obscure viewing and how
Clouds and rain block stars
Ice particles
Heat can cause disruption in atmosphere so stars appear to twinkle
What landscapes block stars
Mountains and trees
