The Welsh Government funding for Universe in the Classroom ended in June 2018. We have left this site available as an archive of the project.
Different parts of the planet experience different times, when it’s lunchtime in Wales, children in Australia are already fast asleep! Time zones are an important, but confusing concept. This activity uses hands-on demonstrations to explain the motion of the Earth and the need for different time zones in a clear and understandable way.
Towns and cities around the world used to set their clocks by the Sun, but dawn and dusk occur at different times in different places because of the Earth’s rotation. The long travel times and lack of long-distance communications back then meant that the time differences were barely noticeable. The need for standard time zones didn’t emerge until the 1800s, with the spread of high speed transportation systems.
In 1884, an international panel decided upon the system of time zones that is essentially the one we still use today. Time zones are based on the fact that Earth moves through 15 degrees of longitude each hour. Therefore, there are 24 standard time zones (24 hours x 15º = 360º).
Time zones are counted from the Prime Meridian which is 0º longitude. The Prime Meridian runs through Greenwich, England. However, in practice, the shape of time zones has been changed to match internal and international political borders. Some countries have non-standard time zones, usually with a 30-minute offset, although a few have a 45-minute offset.
UTC (Universal Time Coordinated) is the common time standard across the world. The definition for time zones can be expressed as UTC ± n, where n is the offset in hours. For example, GMT = UTC ± 0, but BST = UTC + 1:00.
|Siding Springs||Eastern Australia|
2)In this demonstration your lamp will act as the Sun. Set up a lamp on a table where the class can watch. Note: If the class is unfamiliar with day and night, re-cap this with a short demonstration first.
Begin by asking the class to locate your school on your globe. Position the globe so that your school is directly facing the lamp. This position represents midday at your school.
Ask your students whether they can rotate the globe to show the current time.
Note: The Earth rotates in an anticlockwise direction on its axis.
Now draw your students’ attention to the observing sites marked on your globe. Hold the globe in position and ask the following questions: Can the class estimate the time at each site? (For younger children ‘day’ or ‘night’ will suffice.) Which telescopes could be used to carry out observations at this time?
Turn the globe so that your school is facing directly away from the lamp. Explain that this set up shows their school at midnight. Ask for a volunteer to look around the Earth ball. Ask them which observatories can observe the night sky now and which are no longer available?
Explain that LCOGT has observatories all over the world so that they can keep an eye on the Universe no matter what time of day it is! This way we won’t miss anything, such as a star suddenly exploding!
For the next part of the activity, hand each student a Time Zones Student Worksheet.
Explain that the Earth has been divided into 24 segments, separated by imaginary lines running from the North Pole to the South pole around the planet. Demonstrate longitude on the globe.
Note: Longitudes run from North to South, intersecting the equator.
Ask your students why there are 24 time zones. The answer is that there are 24 hours in a day.
For more advanced students you can also explain that each of the 24 time zones (theoretically) covers 15 degrees longitude of the Earth. Ask them to multiply 24 by 15 (24 times zones covering 15 degrees). The answer is 360, which is the number of degrees in a circle (or the circumference of the planet.)
Ask the students to mark the line running down the centre of their worksheet in a bright colour.
Ask the class to label the line the ‘Prime Meridian’. Explain the Prime Meridian runs right through Greenwich near London.
The Earth rotates in an anticlockwise direction so moving East from the Prime Meridian we add one hour for every time zone. Moving West, we subtract one hour for every time zone. E.g. if it’s 11am (11:00) along the Prime Meridian, it will be 8pm (20:00) in Tokyo which is 9 segments East.
Ask your students to work out which segment your school is located within and note the current time (rounded to the nearest hour) in the correct segment in your sheet. Label this ‘My School’ or similar.
Using that time as a baseline, ask the students to work out the current time at each location and LCOGT observatory on their worksheet and write their answer in the space indicated.
Now allow the class to check their answers using a globe and lamp. Position the globe and lamp to show the current time. Does it look like the observatories are positioned at the right place for the times they have calculated? (E.g. if an observatory is at 3am it should be in darkness, an observatory at 11am should be experience daytime.)
|Observatory or City||Location||Time Zone|
|Siding Springs||Eastern Australia||UTC+10:00|
|New York||New York, USA||UT-04:00|
Now that the students understand that the LCOGT network provides 24-hour access to the night sky, carry out a real-time observing session using an available robotic telescope. You will need to reserve a slot in advance. To do this, contact your Project Coordinator with the time and date for your slot. To decide what targets to observe, ask the students to discern which telescopes could carry out the observation right now. The first student to correctly name an available telescope gets to choose which object you observe.
KS2 Science in the Welsh National Curriculum “Sustainable Earth: the daily and annual movements of the Earth and their effect on day and year length”