PHYSICS · Stage 7 · Chapter 5: The Earth in Space
Physics 5.9 Using planetary data — Analysing Orbital Period, Distance and Temperature
5 min read 7 parts Lesson 9 of 11
Lesson summary
Physics 5.9 Using planetary data — Day Length, Year Length and Axis Tilt — Alhussan International Academy — Physics (Stages 7–9) notes: Distinguish primary from secondary sources of data and use planetary data tables to answer questions.Data = observations or measurements recorde…
- Primary source
- Use in astronomy
- Importance
- Similar tilt
- Small tilt
- Large tilt
Section 1 of 7Primary and secondary sources
- Data = observations or measurements recorded in an experiment
- Recording
- scientists record data in tables and display them using charts or graphs
- Primary source
- experiments and fieldwork are primary sources, where you collect the data yourself
- Secondary source
- a book or the Internet contains data that other people have collected
- Use in astronomy
- questions about planets cannot be answered by experiments in a laboratory, so secondary data are used
Section 2 of 7Checking data
- Importance
- data must be checked whether they are primary or secondary
- Methods of checking
- Repeat an experiment.
- Look at more than one secondary source to check that the data are the same.
Section 3 of 7Day length and year length
- Day = the time a planet takes to spin once on its axis, which is 24 hours on Earth
- Year = the time a planet takes to go once around the Sun, which is 365 days (1.00 year) on Earth
- Question
- the data can be used to find whether day length on other planets is related to year length
Section 4 of 7Spin time and orbit time of the planets
| Planet | Time to spin once on its axis (hours) | Time to go once around the Sun (years) |
|---|---|---|
| Mercury | 1416 (59 days) | 0.24 |
| Venus | 244 days | 0.69 |
| Earth | 24 | 1.00 |
| Mars | 25 | 1.88 |
| Jupiter | 10 | 11.86 |
| Saturn | 11 | 29.46 |
| Uranus | 17 | 84.01 |
| Neptune | 16 | 164.80 |
- Year length
- it increases from Mercury to Neptune, so planets further from the Sun take longer to go once around it
- Day length
- there is no simple relationship between the time to spin once and the time to go once around the Sun
Section 5 of 7Seasons and axis tilt
- Cause
- seasons on Earth are due to the tilt of the Earth's axis
- Tilt data
- the angle at which the axis of each planet is tilted can be found on websites and compared
- No tilt
- a planet with no tilt, such as Mercury (0°), has no seasons
- Similar tilt
- planets with a tilt close to the Earth's 23.5° have seasons similar to Earth's
- Small tilt
- a planet with a small tilt, such as Jupiter (3.1°), has seasons that are hardly noticeable
- Large tilt
- a planet with a very large tilt, such as Uranus (97.9°), has seasons very different from the Earth's
Section 6 of 7Axis tilt of the planets
| Planet | Angle of tilt (°) |
|---|---|
| Mercury | 0 |
| Venus | 177.4 |
| Earth | 23.5 |
| Mars | 24.0 |
| Jupiter | 3.1 |
| Saturn | 26.7 |
| Uranus | 97.9 |
| Neptune | 28.8 |
- Retrograde spin
- Venus (177°) and Uranus (98°) have tilts shown with a second angle of −3° and −82° in the diagram
- Not to scale
- a diagram that is not to scale cannot show real sizes or distances
Section 7 of 7Presenting secondary data
- Diagrams
- data are not always presented in a table, so numbers taken from a diagram can be put into a table
- Re-displaying
- secondary data may need to be shown in a different way, such as on a chart or a graph
- Units
- table headings should include units such as hours, days and years
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