Q1.
Collect information about the temperature and size of the planets in the solar system, and check if they have an atmosphere. You may collect this information from books in your school library, trusted websites, or discuss with your teachers. Fill out the missing information in Table 13.2.
Answer
Table 13.2 completed. The values already printed in your book are shown in normal type; the ones you have to fill in are in orange.
| S.No. | Planet | Average temperature (°C) | Radius, compared to the Earth | Has an atmosphere? |
|---|---|---|---|---|
| 1. | Mercury | 170 | 0.38 | No |
| 2. | Venus | 450 | 0.95 | Yes |
| 3. | Earth | 15 | 1 | Yes |
| 4. | Mars | –65 | 0.53 | Yes (about 100 times thinner than Earth's) |
| 5. | Jupiter | –110 | 11 | Yes |
| 6. | Saturn | –140 | 9 | Yes |
| 7. | Uranus | –195 | 4 | Yes |
| 8. | Neptune | –200 | 4 | Yes |
What the completed table shows. Read it as three patterns, not eight rows:
- Temperature falls as you move outward — 170, 15, –65, –110, –140, –195, –200 — because the energy a planet gets comes from the Sun and spreads out over a larger and larger sphere with distance.
- There is one exception, Venus at 450 °C. It is not the closest planet, yet it is the hottest. Its thick carbon dioxide atmosphere traps the heat.
- Size sorts the planets into two families. Radii of 0.38 to 1 are the small rocky planets (Mercury, Venus, Earth, Mars); radii of 4 to 11 are the large gas planets (Jupiter, Saturn, Uranus, Neptune).
Tip: Different sources give slightly different average temperatures, especially for Mercury, whose day and night sides differ enormously. Write down the source you used next to your value — that is how scientists report data.