This page lists questions about "days" that are answered elsewhere.
Select a question to go to its answer. The questions are:
-  Why are there usually two high tides and two low tides each day?
-  Are the length of the day and of the night averaged over a whole year 12 hours each, at all places?
-  What is the formula for the boundary between day and night on Earth?
-  Why can't I see a Full Moon during the day?
-  When does the Sun rises or set the earliest or the latest in the day?
-  When are the shortest and longest days?
-  How many hours, minutes, and seconds are there in a day, exactly?
-  How long do day and night last on the Moon?
-  Where can I find the directions of moonrise and moonset for my town for all days of the year?
-  Why do the lengths of the day and night change the quickest around the equinoxes and the slowest around the solstices?
-  Why hasn't someone proposed to skip a leap day every 128 years instead of every 400 years? Wouldn't that be more accurate?
-  What is the name for the Moon that is seen in full daylight?
-  Why do some months have 31 days but other months do not?
-  If I travelled at 100 kmph, how many days would it take to reach the Sun?
-  Do the nighttime and daytime Moons look alike?
-  Why is the bissextile day always added to February and never to another month?
-  Why does the direction where the Moon rises change a lot from day to day?
-  Why does a new calendar day and therefore also a new calendar year begin at midnight?
-  Who discovered that the Earth rotates on its axis once each day?
-  You mention that day and night are always 12 hours long at the equator and everywhere at the equinoxes, but your sunrise and sunset tables give the length of the day as greater than 12 hours at those dates and locations. How come?
-  How many hours a day does an astronomer work?
-  Does the clock run equally fast whether it is Daylight Savings Time or Standard Time?
-  Does the length of the day and of the night vary on the other planets (for example, Mars) like it does on Earth? How do I calculate those?
-  Can one see stars during the day, for example through a dark smoke stack?
-  How can there be light that started travelling when the Universe was much smaller and younger than today and yet only reaches us today?
-  On which two days of the year is the Sun straight above the equator?
-  In what years does February have five Sundays? When will this occur again?
-  Why is it that shortly after 21 December the Sun rises and sets later every day? And also after 21 June?
-  What are the rotation periods (days) of the planets?
-  When in the past was Daylight Savings Time in effect in the Netherlands?
-  Why do we have Daylight Savings time?
-  Are days and nights always 12 hours long on the equator?
-  How come the night and the day both last 12 hours everywhere on Earth on 21 March and 23 September?
-  When is the first day of the month of Ramadan?
-  How many days, hours, and minutes does the Earth take to rotate around the Sun?
-  What causes night and day?
-  Why don't you see any stars during the day? Where are the stars then?
-  What is the oldest method for estimating the time of day?
-  At what time does the Sun set on Wednesday 16 April 2003?
-  What are the polar day and night and how do they arise?
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Last updated: 2016−04−26