Activity for JessWelchâ€
| Type | On... | Excerpt | Status | Date |
|---|---|---|---|---|
| Question | — |
What determines the length of a day on a planet? The length of a day on different planets in the solar system varies a lot. For instance, Mars' day is about the same length as Earth, while a day on Venus is equivalent to 243 Earth days (source). And Jupiter rotates about 143 times faster than Mercury. What determines the length of a day on a part... (more) |
— | about 10 years ago |
| Question | — |
Are invisible creatures theoretically possible? Would it be possible for a corporeal alien with a solid physical body (it must be able to touch and interact with the world) to exist but remain invisible to humans? My understanding of optics is that if a material doesn't absorb or reflect light in the visible range, it would be invisible to human... (more) |
— | about 10 years ago |