GCSE (9-1) Astronomy Distance Learning

Home , Equation of time, Local mean time

New Pupil Toolkit for GCSE (9-1) Astronomy

GCSE (9-1) Astronomy

Pupil Worksheet

Week 39 Topic 4.3

Spec. refs 4.2, 4.3, 4.4, 4.5, 4.6

1. Which time is given on a sundial? Choose from:

Apparent Solar Time Mean Solar Time Universal Time

Your answer: ...... (1)

2. The image shows a sundial and a carving showing the Equation of Time (EOT).

The EOT is used to convert from

x A Apparent Solar Time to Mean Solar Time

x B Greenwich Mean Time into Apparent Solar Time

x C Local Mean Time into Apparent Solar Time

x D Mean Solar Time into Local Mean Time (1)

New Pupil Toolkit for GCSE (9-1) Astronomy © Mickledore Publishing 2017 New Pupil Toolkit for GCSE (9-1) Astronomy

3. The graph shows how the Equation of Time varies during the course of one year.

Sun fast

/ min Time of Equation Sun slow

Which of the following statements is INCORRECT?

x A During February, the Apparent Sun lags behind the Mean Sun.

x B During November, the Apparent Sun is ahead of the Mean Sun.

x C During May, the Mean Sun is ahead of the Apparent Sun.

x D On four days of the year, the EOT is zero. (1)

4. What is the name of the chart shown below?

Sun fast EOT/min Sun slow

/ of Sun Declination

Choose from:

astrolabe astrogram analemma

Your answer: ...... (1) New Pupil Toolkit for GCSE (9-1) Astronomy © Mickledore Publishing 2017 New Pupil Toolkit for GCSE (9-1) Astronomy

5. On a day when the Equation of Time is +6 min, a sundial reads 11:30.

Calculate the Mean Solar Time at the location of the sundial.

Your answer: ...... (2)

6. On a day when the Equation of Time is -12 min, a sundial reads 14:15.

Calculate the Mean Solar Time at the location of the sundial.

Your answer: ...... (2)

7. A teacher asked her class to tweet the possible reasons for the annual variation in the Equation of Time.

Here are some of the tweets from the students:

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

The Earth’s axis precesses

Place a tick in the box of each correct tweet. (4)

8. Which of the following is the same as Universal Time?

x A Apparent Solar Time

x B Greenwich Mean Time

x C Local Mean Time

x D Mean Solar Time (1)

New Pupil Toolkit for GCSE (9-1) Astronomy © Mickledore Publishing 2017 New Pupil Toolkit for GCSE (9-1) Astronomy

9. Which of Kepler’s laws implies that the speed of the Earth in its orbit around the Sun varies?

Choose from:

first law second law third law

Your answer: ...... law (1)

10. The graph shows how the two independent factors combine to give the annual variation in the EOT.

Earth’s elliptical orbit Obliquity of ecliptic Combination

EOT / minEOT

month of year

Diagram adapted from website of Hartebeesthoek Radio Astronomy Observatory, with gratitude.

A student suggests that at the equinoxes and solstices, the EOT due to the tilt of the Earth’s axis is zero.

Explain whether you think the student is correct or not.

......

...... (4)

11. Which of the following statements about the apparent motion of the Mean Sun during the course of one year is INCORRECT?

x A It always lies on the celestial equator.

x B Its declination is always zero.

x C Its right ascension continuously decreases.

x D Its speed is constant. (1)

12. During which months of the year does the Earth’s speed continuously increase?

x A April and May

x B December and January

x C June and July

x D October and November (1)

Solutions

1. Apparent Solar Time (1 mark)

2. A (1)

3. C (1)

4. analemma (1)

5. 11:24 (2); allow (1) mark for 10:36

6. 14:27 (2); allow (1) mark for 14:03

7. All first four boxes ticked (1) for each. Deduct (1) if last box (precession) is ticked. Maximum 4 marks

8. B (1)

9. second (law) (1)

10. The student is correct (1); the red dashed/dotted line shows the variation of the EOT due to the Earth’s axial tilt/obliquity of the ecliptic (1); it crosses the time-axis / has a value of zero/0 (1) in mid-late March, June, September and December / on dates corresponding to the solstices and equinoxes (1). Maximum 4 marks

11. C (1)

12. D (1)

Your score: / 20