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Astronomy GCSE (Edexcel) > Ay [T2] - The Night Sky > Flashcards

Ay [T2] - The Night Sky Flashcards

1
Q

What is a star cluster?

A

A cluster of stars that formed from the same cloud of dust. They are very close together in the night sky.

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2
Q

What is a constellation?

A

A pattern that humans have made with stars in the sky.

There’s nothing to link those stars together.

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3
Q

What is an asterism?

A

Smaller patterns within constellations (eg: Orion’s Belt, which is within Orion) that aren’t official constellations.

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4
Q

What is a nebula?

A

Nebulae are huge clouds of dust and gas that are responsible for the birth of stars. They’re often very beautifully coloured.

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5
Q

What is the radiant of a meteor shower (and why do meteor showers have them)?

A

The radiant of a meteor shower is the constellation the meteors appear to come from.

Meteors are formed from the same comet every year, therefore they appear to come from the same place in the night sky.

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6
Q

What is a supernova?

A

A supernova occurs when a star explodes.

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7
Q

How would you structure a 6 mark question asking you to evaluate the suitability of the suggested celestial objects based on observations made?

A

Suggested object is likely to be _____ because it is ______________.

The suggestion in (number) is incorrect because a _____ would not ___________. A suitable alternative could be _______.

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8
Q

Is Cassiopeia a constellation or an asterism?

A

Constellation

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9
Q

Is Cygnus a constellation or an asterism?

A

Constellation

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10
Q

Is Orion a constellation or an asterism?

A

Constellation

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11
Q

Is The Plough a constellation or an asterism?

A

Asterism

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12
Q

Is The Southern Cross a constellation or an asterism?

A

Constellation

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13
Q

Is The Summer Triangle a constellation or an asterism?

A

Asterism

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14
Q

Is The Square of Pegasus a constellation or an asterism?

A

Asterism

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15
Q

How do you find Sirius in the night sky quickly?

A

Follow Orion’s Belt southwest. The first bright star you see is Sirius.

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16
Q

How do you find Polaris in the night sky quickly?

A

Follow the edge of the pan of The Plough northeast. The first bright star you see is Polaris.

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17
Q

How do you find Arcturus in the night sky quickly?

A

Follow the handle part of the Plough (from Alkaid) southwest and curved slightly. The first bright star you see is Arcturus

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18
Q

What’s an easy way to remember how to find Polaris and Arcturus?

A

Follow the PAN to Polaris.

Follow the ARC to Arcturus.

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19
Q

How do you find Aldebaran in the night sky quickly?

A

Follow Orion’s Belt up and the first brightest star is Aldebaran.

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20
Q

How do you find The Pleiades in the night sky quickly?

A

Follow Orion’s Belt up and the first cluster of stars is The Pleiades.

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21
Q

How do you find Fomalhaut in the night sky quickly?

A

Follow the right side of the Square of Pegasus (from Markab) southeast and the first brightest star is Fomalhaut.

22
Q

How do you find The Andromeda Galaxy in the night sky quickly?

A

Follow the left most point of the Square of Pegasus left and the Andromeda Galaxy will be the slightly longer bright light.

23
Q

What is the Ecliptic?

A

The path of the sun across the night sky

24
Q

What is the celestial equator?

A

The equator on the celestial sphere

25
Q

What are the North Celestial Pole (NCP) and the South Celestial Pole (SCP)?

A

The north and south pole on the celestial sphere

26
Q

What is declination?

A

Declination (dec) is equivalent to latitude on Earth, measured in degrees (+ and - indicate N and S)

27
Q

What is right ascension?

A

Right ascension (RA) is equivalent to longitude on earth, measured eastwards from the First Point of Aries, typically measured in hours and minutes

28
Q

Why do we need to wait 30 minutes after going outside before observing stars?

A

Dark adaptation.

It takes a certain amount of time for our eyes to adjust to low levels of light (~30mins)

29
Q

Why do we measure RA in hours and minutes?

A

1RA would take 24 hours

30
Q

What are the following 3 conversions:

360° = ?h
1h = ?°
1 min = ?°

A

360° = 24h
1h = 15°
1 min = 0.25°

31
Q

How do you convert between degrees and hours?

A

÷15 for degrees to hours
÷0.25 for degrees to minutes

×15 for hours to degrees
×0.25 for minutes to degrees

32
Q

Why do we measure RA going left

A

We are INSIDE the celestial sphere

33
Q

What is altitude?

A

How high up a star appears to be for you (the observer) in the sky

34
Q

What is azimuth?

A

Where in NESW the stars appears to be (relative to your, the observer’s, position)

35
Q

What is diurnal motion?

A

The daily motion of stars across the night sky

36
Q

What is a solar/synodic day and how long is it?

A

The time taken for the sun to appear in the same position = 24hours (~361°)

37
Q

What is a sidereal day and how long is it?

A

The time taken for the earth to rotate through 360° = 23 hours 56 minutes

38
Q

Define zenith

A

The point in the celestial sphere directly above the observer

39
Q

Define nadir

A

The point in the celestial sphere directly below the observer

40
Q

Define meridian

A

An imaginary circle that runs from north to south through the zenith and nadir

41
Q

What is culmination?

A

The highest point of any object in the night sky. It’s always due south and always crosses the observer’s meridian

42
Q

Define Local Sidereal Time (LST)

A

The LST of an observer is the RA of a star that lies on the observer’s meridian at a given moment in time

43
Q

What is an hour angle and it’s equation?

A

The hour angle tells us how long since a star last crossed the observer’s meridian.

Hour angle = LST - RA of the star

44
Q

What does it mean if an hour angle is a negative number

A

How long UNTIL the star will cross the meridian

45
Q

What are circumpolar stars?

A

Circumpolar stars never set below the horizon

46
Q

How do you calculate if a star is circumpolar?

A

Polar distance (90° - dec) < latitude of observer

If this is true, the star is circumpolar. If not, then it isn’t.

47
Q

What is the upper and lower transit of a star?

A

Upper transit = highest point in the sky (star culminates here)

Lower transit = lowest point in the sky

48
Q

What is the altitude (at upper and lower transits) equal to?

A

Altitude (at upper and lower transits) = observer’s latitude ± polar distance

49
Q

When is the best time to observe an object in the night sky and why?

A

When it is close to culmination because colours can then be detected and more detail can be resolved

50
Q

What is dark adaptation and how long does it take to occur?

A

The eyes becoming fully adapted to the dark, which takes about 20-30 minutes

Astronomy GCSE (Edexcel) (9 decks)

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