GPS为什么至少需要4颗卫星才能定位？
Why does GPS need at least four satellites to locate you?
3颗卫星可算出你所在的球面交点（三维位置），但手机时钟不够准，第4颗用来校正时间误差，才能精确到米。
Three satellites give your 3D position by intersection, but the receiver clock is imprecise, so a fourth corrects the time error and pins you to meters.
难度 专业 · 适合 高中(15-18)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Tarbuck & Lutgens,《Earth Science》第14版,Pearson,2015
E. J. Tarbuck and F. K. Lutgens, Earth Science, 14th ed., Pearson, 2015
#GPS #卫星
为什么经度能用来算时差，纬度却不能？
Why can longitude be used for time differences but latitude cannot?
地球自西向东转，不同经度见到太阳的时刻不同，所以每差15°大约差1小时；纬度是南北位置，和“几点钟”无关。
Earth spins west to east, so different longitudes see the Sun at different times—about 1 hour per 15°. Latitude is north–south and unrelated to clock time.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Tarbuck & Lutgens,《Earth Science》第14版,Pearson,2015
E. J. Tarbuck and F. K. Lutgens, Earth Science, 14th ed., Pearson, 2015
#经度 #时差
等高线地图上，一条“V”字形代表什么？
On a contour map, what does a “V” shape mean?
等高线往高处凸出的“V”字通常代表山谷（河流常沿此流）；若往低处凸出，则多是山脊。看凸向就能判断地形。
A “V” pointing to higher ground usually marks a valley (where a stream often runs); a “V” pointing downhill marks a ridge. The direction tells the landform.
难度 进阶 · 适合 初中(12-15)
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Tarbuck & Lutgens,《Earth Science》第14版,Pearson,2015
E. J. Tarbuck and F. K. Lutgens, Earth Science, 14th ed., Pearson, 2015
#等高线 #山谷
国际日期变更线为什么会让一天“消失”或“重复”？
Why can the International Date Line make a day “disappear” or “repeat”?
从东向西跨过这条线要把日期加一天，从西向东则减一天。坐飞机跨越时，可能“跳过”或“过两次”某一天。
Crossing it westward adds a day, eastward subtracts one. A flight across it can make you “skip” a date or experience one twice.
难度 进阶 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Tarbuck & Lutgens,《Earth Science》第14版,Pearson,2015
E. J. Tarbuck and F. K. Lutgens, Earth Science, 14th ed., Pearson, 2015
#日期变更线 #时区
时区是怎么划分的，中国横跨几个时区？
How are time zones divided, and how many span China?
地球按经度每15°划一个时区，全球约24个。中国横跨5个地理时区，但全国统一用北京时间。
The world is split into about 24 zones of 15° each. China spans five geographic zones but uses a single “Beijing Time” nationwide.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Tarbuck & Lutgens,《Earth Science》第14版,Pearson,2015
E. J. Tarbuck and F. K. Lutgens, Earth Science, 14th ed., Pearson, 2015
#时区 #北京时间
什么是“海拔”，珠峰的高度以什么为基准？
What is “elevation” and what is Everest's height measured from?
海拔是某点高出平均海平面的垂直距离。珠峰高度以黄海平均海平面为基准测算，约8849米。
Elevation is the vertical distance above mean sea level. Everest's height is measured from the Yellow Sea mean sea level, about 8,849 m.
难度 入门 · 适合 大众
CC BY 4.0 · 已核验 · Verified 2026-08-23
来源 · Source
Tarbuck & Lutgens,《Earth Science》第14版,Pearson,2015
E. J. Tarbuck and F. K. Lutgens, Earth Science, 14th ed., Pearson, 2015
#海拔 #基准面