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3 votes

Most established length of Gleissberg Cycle

The observation is not of an exact "period" but more generally that 3-5 sunspot cycles with lower activity tend to be followed by 3-5 with stronger activity. Since a cycle is roughly 11 ...
James K's user avatar
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4 votes

What can be learned from viewing the sun on earth during a total eclipse that cannot be studied by spacecraft in orbit?

"is there any way to position a probe so that it constantly experiences totality? Such as in Lagrange point L2 of some planet?" Careful reading of your linked Wikipedia page shows that the ...
Fe2O3's user avatar
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14 votes

What can be learned from viewing the sun on earth during a total eclipse that cannot be studied by spacecraft in orbit?

It is true that many of the things that we used to use eclipses for can now be done from space, continuously. Eclipses are still important because they are usually much more easily accessible than ...
James K's user avatar
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3 votes

How did the ancient cultures determine that the year was actually a fraction of an extra day beyond 365 days?

Count the days. Many days. You cannot expect high accuracy if you measure the thickness of a single sheet of paper with a ruler. You can improve it greatly if you stack 1000 sheets, measure the total ...
Eric Duminil's user avatar
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1 vote

How did the ancient cultures determine that the year was actually a fraction of an extra day beyond 365 days?

For long-term consistent time measurements there would usually be markings put on the walls of irrigation canals which would cast a sharp shadow against the opposing wall of the stone-walled canal or ...
Amrita Bithi's user avatar
3 votes

How did the ancient cultures determine that the year was actually a fraction of an extra day beyond 365 days?

How do you observe those Sunrises and sunsets are pretty obvious. However, in order to accurately measure the length of day versus night, you need a type of clock that's not a sundial. A water ...
dan04's user avatar
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