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GCSE Edexcel Astronomy > (A) paper one questions i dont understand > Flashcards

(A) paper one questions i dont understand Flashcards

1
Q

How are mountains on the moon thought to be formed?

A

Formed by impacts releasing magma under the early lunar surface

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2
Q

Name three factors we need to take into account whilst studying precession

A
  1. Earth’s elliptical orbit
  2. Moon has its own precession
  3. Moon has an orbit around Earth at a different degree of inclination to the orbit
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3
Q

What causes sundial accuracy?

A
  • Eccentricity of Earth’s orbit
  • Earth’s axis
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4
Q

What is an equinox?

A

When the sun passes over the celestial equator

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5
Q

What happens during a conjunction?

A

When a planet is in front of or behind the sun as viewed from Earth

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6
Q

Define culmination

A

When a star or another body reaches the observer’s meridian

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7
Q

What is co-declination?

A

Distance between NCP and star

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8
Q

What is the formula for co-declination?

A

90 - dec

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9
Q

When does upper culmination take place?

A

When right ascension = local sidereal time

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10
Q

What did Kepler discover using Tycho’s observations?

A

Noticed that planets follow elliptical orbits

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11
Q

What is Kepler’s third law?

A

The square of the orbital period (t) is directly proportional to the cube of its mean distance (r) from the sun

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12
Q

What is the difference between the equatorial coordinate system and the horizontal coordinate system?

A

HCS is local whereas ECS is applicable to any location

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13
Q

What causes lunar libration in latitude?

A
  • Moon’s equator is inclined to the plane of its orbit by 1.5 degrees
  • The plane of the Moon’s orbit is inclined by 5.1 degrees to the ecliptic
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14
Q

What causes lunar libration in longitude?

A

Moon’s varying speed in its orbit

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15
Q

What were the inaccuracies in Aristarchus’s method of measuring the distance from the Earth to the Sun?

A

Measuring angle too close to 90 degrees

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16
Q

What did Eratosthenes do?

A

Measured the circumference of the Earth

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17
Q

What was the equation Eratosthenes used?

A

circumference of the Earth/ distance from Syene to Alexandria = 360/7

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18
Q

Libration in longitude is caused by the Moon’s elliptical orbit around the Earth.
Explain the connection between this type of libration and the Moon’s orbit.

A
  • During its elliptical orbit, the Moon’s orbital speed changes.
  • The Moon’s (axial) rotation remains constant
  • This allows parts of the Moon’s eastern and western limb to be visible (during
    different times of the lunar month).
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19
Q

Which two of Aristarchus’ deductions formed the basis of his suggestion that the Sun was at the centre of the Earth - Moon - Sun system?

A
  • (large) distance to the Sun
  • (large) size of Sun compared with Earth
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20
Q

When does an annular solar eclipse occur?

A

An annular eclipse occurs when the Moon is close to apogee and so appears slightly smaller than ‘usual’/the Sun, allowing the Sun to appear as a thin annulus.

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21
Q

What are the possible reasons for the annual variation in EOT?

A
  • The Earth’s axis is tilted to the ‘vertical’
  • The Earth’s orbit around the Sun is elliptical
  • The obliquity of the ecliptic
  • The Earth’s speed changes in its solar orbit
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22
Q

In which compass direction do the planets ‘wander’ from night to night in the sky?

A

Eastwards

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23
Q

In which part of the sky are the planets observed?

A

From the zodiacal band

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24
Q

What are the equatorial coordinates of the First Point of Libra?

A

RA = 12 h 0 min, dec = 0°

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25
Q

What is the declination of the Sun on June 21st?

A

+ 23.5°

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26
Q

In which constellation is the First Point of Aries located?

A

Pisces

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27
Q

Which 3 stars form the Summer Triangle asterism?

A

Altair, Deneb and Vega

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28
Q

Which bright star can be found by following the two right-hand stars in the Plough?

A

Polaris

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29
Q

The three stars in the ‘handle’ of the constellation Plough indicate the location of a bright star. What is the name of this star?

A

Arcturus

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30
Q

Why do you think that there is a range of names of constellations and asterisms among different cultures?

A
  • When asterisms and constellations were first named, there was very little mass communication: different cultures were relatively isolated compared with today, and so were unable to share/exchange stories, myths, and legends.
  • Different cultures were able to see different stars and identify patterns because of
    different geographical locations.
  • Different cultures used different stories, myths, and legends on which many of their
    asterisms and constellations were named.
31
Q

What is used to mark 0h 0min in RA?

A

First Point of Aries

32
Q

What is the formula for altitude?

A

altitude = latitude ± polar distance

33
Q

What astronomical objects can be seen on a planisphere?

A

Constellations, Messier objects and stars

34
Q

When does a planet have its largest speed in orbit and why?

A

Perihelion, because the gravitational force acting on the body in orbit is larger than when it is during aphelion

35
Q

The most southerly latitude where the Sun is above the horizon for 24 hours on 21st June is called the

A

Arctic Circle

36
Q

Generally, the sidereal period of the superior planets is larger than their synodic period.
Explain why the sidereal period would be larger than the synodic period.

A
  • Superior planets take longer to orbit the Sun than the Earth does
  • So they will return to the same position in relation to the Earth before they complete a single orbit
  • which means that the superior planets have multiple smaller synodic periods within the time it takes to complete one larger sidereal period
37
Q

An astronomer claims to have discovered an object that orbits the Sun at a mean distance of 500 AU.
The astronomer thinks that the synodic period is close to 1 year.
Explain why the synodic period for this object would be close to 1 year.

A
  • A value of 500AU is towards the edge of the solar system
  • So the object will not have progressed in its orbit much in the time it takes the Earth to orbit the Sun
38
Q

How would a satellite appear to the naked eye?

A

Point of light moving quickly

39
Q

Describe two ways in which the far side of the Moon appears different to the side
facing the Earth.

A
  • Far side of Moon has fewer maria
  • Far side has more highland/terrae
  • Far side appears lighter
  • Far side of Moon has more craters
40
Q

How do we calculate observer’s latitude?

A

90 - ALT + DEC

41
Q

What is local sidereal time?

A

The time at an observer’s location is measured by the right ascension (RA) of the observer’s meridian. It is the RA of the meridian line at that point in time.

42
Q

What is the hour angle?

A

The number of hours it will take for that object to reach the observer’s meridian OR the number of hours since it passed the observer’s meridian.
It is the difference between the RA of
the meridian and the RA of the object.

43
Q

How do we calculate the next culmination of a star that has already culminated?

A

If the object has passed the meridian, subtracting the value of the hour angle from 23hrs56mins4sec gives the time until it next culminates.

44
Q

Explain why precession causes variation in pole stars.

A
  • Earth’s axis points to the pole star rather than the pole of the ecliptic which stays fixed
  • which means that precession causes the Earth’s axis to circle around the pole every 26000 years
  • so the axis will point to different stars at different times
45
Q

Explain why precession would cause stars to be misaligned with monuments

A
  • The direction of axial tilt has shifted since the building of the monument
  • so the star will have a different location now
46
Q

Explain why precession would cause stars to be misaligned with monuments

A
  • The direction of axial tilt has shifted since the building of the monument
  • so the star will have a different location now
47
Q

Sailors on a ship can use observations of the Sun and the time on an accurate
clock to find their longitude.
Describe in detail this method for finding longitude.

A
  • Record time of local noon / Sun culminates (1)
  • Measure the difference between recorded time (local
    noon) and 12:00 (GMT) (1)
  • A difference of 4 minutes corresponds to 1o of longitude
    East or West (of the meridian)
    or
    A difference of 1 minute corresponds to 0.250 of
    longitude East or West (of the meridian) (1)
48
Q

State two differences between seeing conditions and weather.

A
  • Seeing is a measure of how still a star/object will appear (allow how much stars appear to twinkle/atmospheric stability) (1)
  • Weather affects the transparency of the sky (1)
49
Q

Explain what would happen to the appearance of a total solar eclipse if the Moon orbited much closer to the Earth.

A
  • Eclipses last longer
    or
  • Eclipses occur more frequently
    or
  • Corona not visible (during totality) (1)
  • because Moon appears bigger in the sky (1)
50
Q

State two days of the year when the rising or setting Sun can be used to find the
exact direction of East or West.

A
  • Spring/Vernal Equinox (or 19/20/21 March) (1)
  • Autumn Equinox (or 21/22/23/24 September) (1)
51
Q

Why is Venus best seen at the angle of elongation?

A

This means that Venus appears in a darker sky (1) so contrast is greater

52
Q

Why doesn’t the lunar eclipse happen every month?

A

Total lunar eclipse does not occur unless the Earth, Moon and Sun are aligned (at full Moon) (1)
Because the Moon’s orbit is {tilted/inclined} to {ecliptic/Solar System plane} (1)
Which means that the Moon doesn’t fall in the Earth’s shadow every month (so not always a total eclipse) (1)

53
Q

The appearance of the Moon during a lunar eclipse is evidence that the Earth has a curved surface.
Explain this statement.

A
  • Shadow is curved
  • Curvature of the shadow is different to the curvature of the Moon
54
Q

State one reason why it is hard to obtain an accurate value for the Moon’s diameter using Eratosthenes’ method.

A
  • hard to estimate exact time of contacts
  • slow progress of eclipse
  • fuzzy edges of shadow regions
  • weather conditions
  • compound error from diameter of Earth.
55
Q

The position of the First Point of Aries moves very slowly amongst the stars.
This movement is called precession.
Explain the cause of precession.

A
  • rotation/’wobbling’ of Earth’s polar/spin axis
  • complex gravitational field/forces/’pulls’ of Sun and
    Moon
56
Q

Explain why most places near the sea have two high tides each day.

A
  • The gravitational pull of Moon
  • Creates two areas of high water level on Earth
  • Each point on Earth rotates through these
    every 24 hours.
57
Q

Alice notices that the level of the sea water at high tide has been getting steadily
higher every day.
She also notices that the Moon is approaching its full phase.
Explain how these two observations are connected

A
  • Use of term ‘spring’ tide
  • Moon and Sun on directly opposite sides of Earth
  • Pulls combine / extra high (and low) ‘bulge’ of water
58
Q

He is shown using his ‘mural quadrant’. This was a very large protractor, reading from 0° to 90° with a radius of about 4 metres.
Using this equipment, he was able to measure the positions of objects in the sky to
a precision of around 8 minutes of arc, without the use of a telescope.
Explain how Brahe was able to make such precise measurements without the
use of a telescope.

A
  • large angle scales
  • Reduces percentage/proportion of error
59
Q

Mars’ position in the sky was very similar for both an elliptical and a circular orbit.
Explain why predictions of the position of Mars in the sky made using a circular orbit are so close to its actual position.

A

Planetary orbits are close to circular
Use of appropriate scientific terminology, e.g. low eccentricity, foci are close together, not very elliptical

60
Q

Explain why calculating Mars’ radius using its sidereal rotation period gives an incorrect value for the average radius of
Mars’ orbit.

A

The student has used synodic (not sidereal) period (Time to return to point on Celestial Sphere) is not time to orbit the Sun.

61
Q

Explain why time zones are used on the Earth

A
  • To ensure that clock time roughly corresponds with the position of the Sun (1)
  • For different locations on the Earth (1)
62
Q

Why does the Moon appear to look different at the summer and winter solstice?

A

At winter solstice the Sun’s altitude is at its greatest below the horizon / at summer solstice the Sun’s altitude is at its smallest below the horizon (1)
Moon is illuminated from different angles (1)

63
Q

For the moons of Uranus, this constant is equal to 0.91 × 10-15 day2/km3
However, this constant cannot be used to calculate the orbital periods of the moons orbiting Saturn.
Explain this statement.

A

Kepler’s law has a different constant/does not equal 0.91 (1)
because Saturn has a different mass/gravitational field to Uranus (1)

64
Q

Pluto has a much larger orbit and takes longer to orbit the Sun than the Earth.
State two other differences between the orbital paths of Pluto and the Earth.

A
  • More eccentric/elliptical
  • Greater variation in speed
  • Greater tilt (to the ecliptic)
  • Pluto has not cleared its orbit.
65
Q

In 2006, Pluto was reclassified as a dwarf planet.
State one reason for this change.

A
  • Has not cleared its orbit of other
    bodies
  • Is part of the Kuiper Belt
  • Is not alone in its orbit
  • Similar/larger bodies in its
    orbit/Kuiper Belt, e.g. Eris
66
Q

Observation of the Earth and Moon system has produced evidence to suggest
that the Giant Impact Hypothesis is correct.
Describe in detail two of these pieces of evidence.

A
  • Chemical (isotopic) composition of lunar rocks (from Apollo missions), e.g. oxygen, KREEP, zinc etc
  • Extremely improbable dynamics of capture
    hypothesis
  • Density/magnetic evidence for unusually small iron core of Moon
  • Analysis of meteorites created by impact.
67
Q

Although Venus orbits the Sun once every 225 days, transits of Venus are
extremely rare. Explain why they are so rare

A

Venus (or Earth) has a tilted orbit/orbital plane compared to each other / ecliptic or
orbits only cross/align in two places

68
Q

Through a small pair of binoculars star X is actually two stars that appear very close together. What is the name of this type of star?

A

Double Star

69
Q

State one way in which a wrinkle ridge of the moon is different from a rille

A

wrinkle ridges are longer / wider / higher /
above the surface

70
Q

State two key pieces of information you can obtain from a planisphere

A
  • Which constellations/stars/nebulae visible
  • Location of constellations/stars/nebulae etc in sky
  • Times of culmination of constellations/stars/nebulae etc
71
Q

Give two pieces of evidence to show that the Earth is not flat

A
  • Images from space
  • Shadow of Earth during partial lunar eclipse
  • Satellite orbits
  • Ships disappear over horizon
72
Q

Describe how the circumference of Earth was first calculated by Greek mathematician Eratosthenes

A
  • Idea of using shadows / solar angles (or lack of them) at two different places 1
  • Difference in angles /shadow lengths
    corresponds to distance between 2 locations 1
  • Extrapolation to a complete circle
73
Q

What is the significance of the ecliptic on the star chart?

A

Shows motion / path of the Sun (over the
course of one year)

GCSE Edexcel Astronomy (22 decks)

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