Sometimes you hear grown-ups say, “I wish there were more hours in the day,” because they can’t finish everything they have to get done before bedtime. Well, just tell them to move to the planet Venus, where the days are really, really long. Venus takes a whole 243 Earth days to spin once through a full day and night. By then Venus has actually traveled all the way around the Sun, as it takes only 224 Earth days to orbit once…on Venus a year is shorter than a day! That’s much more relaxed than traveling to Neptune, where a day speeds through only 16 of our hours, or Jupiter, whose day takes fewer than 10 hours. On the other hand, if you want a long year, Neptune might work well for you: its year is so darn long — 164 of our years — that only in 2010 did it finally finish one full orbit since we first spotted it in 1846. So, if we could just survive the extreme temperatures and poisonous air on these crazy planets, we could get a lot done in a year.
Wee ones: The major planets are Mercury, Venus, Earth (where we live), Mars, Jupiter, Saturn, Uranus and Neptune. How many planets is that?
Little kids: If Jupiter has a 10-hour day and Neptune’s takes 16 hours, how much longer is a day on Neptune? Bonus: If your friend is hanging out on Venus, where 1 day takes 243 of ours, as of tomorrow how many more of our days will he or she have left to finish a “day”?
Big kids: If it’s 6 pm now and Jupiter’s Great Spot is facing us, when will it face us for the 3rd time? (Don’t worry about movement around the Sun and the resulting small change in angle.) Bonus: How many Earth days are in a Venus week, if a “week” there takes 7 Venus days?
The sky’s the limit: If Mercury’s year is 88 days, and Mercury and Venus are currently on the same side of the Sun, when’s the next time they will both be in that same spot again?
Wee ones: 8 major planets.
Little kids: 6 hours longer. Bonus: 242 more days.
Big kids: At 2 pm tomorrow (20 hours from now). Bonus: 1,701 days.
The sky’s the limit: 2,464 days. We need the lowest common multiple of both 88 and 224, i.e. the smallest number of days that’s divisible by both. Both numbers are divisible by 8, so we don’t need to multiply them by each other. We just need a number divisible by both 224 and 11 (1/8 of 88), because the 8 from the 224 will make the product divisible by 88 as well. That gives us 224 x 11, or 2,464 days.