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12 votes

How long does a magnetic pole reversal take to complete?

The entire process appears to take 3,000-4,000 years, according to Valet and Fournier's May 2016 review article "Deciphering records of geomagnetic reversals," which was published in AGU's Reviews of ...
jeffronicus's user avatar
  • 3,486
10 votes

Least populated time-zones

There is one timezone that is completely uninhabited: the UTC-12:00. It covers only two islands: Baker Island and Howland Island that are both uninhabited (owned by US). Because of the weird way ...
Communisty's user avatar
  • 1,064
10 votes
Accepted

Changes in Earth's orbital and rotation speeds

The Earth moves faster around the Sun when it is near its perihelion (the closest point of its orbit to the Sun). And it moves slower when it is further away (aphelion), just as Kepler realized quite ...
Camilo Rada's user avatar
  • 17.7k
8 votes

Is there any DST to ST transition happening at the end of the day?

Per Wikipedia, several countries switch to daylight savings time at midnight. Time jumps from midnight to 1:00 AM in these countries on the date of the switch to daylight savings time. Only Chile, ...
David Hammen's user avatar
  • 23.7k
7 votes

Why do the earth sciences use mega-annum instead of mega-year?

annum (ka, Ma, Ga) Time before present. A point of time in the geological past, measured backwards from now. Often, “now” is defined as the year 1950. year (kyr, Myr, Gyr) A measure of duration, ...
Gimelist's user avatar
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6 votes
Accepted

What happens when the North and South poles flip?

First of all I will try to explain what a geomagnetic pole reversal is. A magnetic pole reversal happens when the magnetic field weakens until it can no longer sustain itself. This can take 1000-3000 ...
trond hansen's user avatar
  • 1,888
6 votes

What are the farthest Time Zone locations?

The original wording of your question revealed that you are missing something about what time zones are, and how they are defined. So let me start from the begin. If you are impatient, you can jump ...
Camilo Rada's user avatar
  • 17.7k
6 votes
Accepted

Why does the earth rotate in correlation with it's rotation around the sun to such precision?

I find it bizarre that the earth rotates at nearly exactly 365 1/4 times per year, requiring an extra day every 4 years. The Earth does not rotate nearly exactly 365 1/4 times per year. That's the ...
David Hammen's user avatar
  • 23.7k
5 votes
Accepted

Seeming correlation between time of day and earthquakes

As noted by Barry Carter, you could take a look at https://www.emsc-csem.org/Earthquake/Map/zoom.php?key=75&typ=NAM#5 to see the earthquakes around San Francisco, with a table below giving the ...
Erik's user avatar
  • 1,999
5 votes
Accepted

How much of one day can be considered nighttime, on average?

To further clarify, assume we are on the equator, I want to know how long a time, as a percentage, you could consider to be nighttime on Earth, with the points in time separating night and day being ...
David Hammen's user avatar
  • 23.7k
5 votes
Accepted

Are the length of seasons the same globally?

As has been noted in a comment, it depends on how you define seasons (see https://earthscience.stackexchange.com/a/2603/111). If seasons are defined in astronomical terms, then they have the same ...
Semidiurnal Simon's user avatar
5 votes
Accepted

Problems when interpolating time series data (average problem)

Is it a solution to multiply the B Average Value with 0.7, so the weighted average value will be 3.5? No, this is not a solution. Doing this effectively assigns a value of zero to the stations that ...
Fred's user avatar
  • 24.7k
5 votes

Will the definition of the second be changed?

Someday in future, the length of a day will be longer than 86400 atomic seconds. Then what should future human do? Having a time standard that works well with the ever improving capabilities of ...
David Hammen's user avatar
  • 23.7k
5 votes

"3.5–1.75 billion years ago" or "1.75–3.5 billion years ago"?

If this is an estimate of the time a given event happened, then it's OK to use the youngest date first. But it's also OK to say it the other way. "The KQUB Formation consists of heavily ...
Spencer's user avatar
  • 3,638
4 votes

Perihelion Vs Aphelion position of Earth

Why is the length of the apparent solar day less at aphelion than when compared to perihelion? The TL;DR version: There's a simple answer to this question, which is that the Earth is orbiting the Sun ...
David Hammen's user avatar
  • 23.7k
4 votes

Why do the earth sciences use mega-annum instead of mega-year?

Annum and year are not the exact same thing. The exact length of a year depends on what exactly you are measuring, whether distance between perihelions, distance between solstices, etc. It also varies ...
James's user avatar
  • 41
4 votes

What does "rapid" mean in terms of igneous rock formation?

Obsidian is volcanic glass of felsic composition (i.e. SiO2-rich) whereas basalt is a volcanic rock which may or may not be (partially) glassy of mafic composition (i.e. SiO2-poor). So when you're ...
Gimelist's user avatar
  • 23.1k
4 votes

How long does a magnetic pole reversal take to complete?

As per our numerical calculations it takes about ~1000 years to completely flip the dynamo, that being said the current models are not even close to the actual parameters in the earth's core because ...
Gaurav Dhama's user avatar
3 votes

When does the International Date Line concept break down?

Time zones and the date line are associated with the geography, not the traveler. In practical and mechanical terms, you don't "gain" or "lose" days by crossing the date line ...
jeffronicus's user avatar
  • 3,486
2 votes

Why would moving the prime meridian hasten the time when it would be necessary to drop a day from the calendar?

There is no basis in logic to have to subtract a day due to a change in the prime meridian. Both the Julian & Gregorian calendars require days to be added, not subtracted. It's why we have leap ...
Fred's user avatar
  • 24.7k
2 votes

Oldest to Newest Bedrock in the USA "road trip"

If you were hoping for a smooth succession from Archean all the way down to Quaternary, you're going to be disappointed. Geology is messier than rocks being serenely laid down continuously through ...
Spencer's user avatar
  • 3,638
2 votes

Precession & Time

I believe the source of your confusion is that you are confusing a sidereal year with a tropical year. The sidereal year, which is the definition most often cited as the standard definition of a year, ...
BillDOe's user avatar
  • 2,187
2 votes

which are the two countries with the flight time between them and time zone differences are equal

I'm not going to look for examples, but there will be some. More interesting is to consider the underlying geometry: At one extreme, if you fly from north to south (or vice versa) you'll experience ...
Semidiurnal Simon's user avatar
2 votes

How fast can water erode stone?

In short, it depends on the type of stone, the energy of impact of the water and for how long water is applied with such an energy of impact. A weak stone such as sandstone will erode more quickly ...
Fred's user avatar
  • 24.7k
2 votes

When does the International Date Line concept break down?

The key is recognizing that as you walk around the pole, you not only cross the IDL. You cross all the other time zone boundaries that also converge to the pole. If you are going east so that you set ...
Oscar Lanzi's user avatar
  • 3,926
1 vote

What is the true time when the sun is directly over Perth given that the W.A. time is taken from Southern Cross

I find the statement that time in Western Australia is based the location of Southern Cross somewhat speculative. Some supportive evidence would improve the question. Given the history of British ...
Fred's user avatar
  • 24.7k
1 vote

What are the farthest Time Zone locations?

Given you are in the UK, ignoring daylight savings, Tonga and Tokelau are in time zones that are 13 hours ahead of the UK (i.e. to the east). To the west, the largest difference in time is 10 hours ...
Fred's user avatar
  • 24.7k
1 vote

which are the two countries with the flight time between them and time zone differences are equal

If you flew from Warsaw, Poland to Lviv, Ukraine the flight time would be one hour and the time difference the two is one hour.
Fred's user avatar
  • 24.7k
1 vote

Why do the earth sciences use mega-annum instead of mega-year?

Yes and no. One annum ago is defined as 365.25 days. But a Julian year is not defined in seconds and so is not an SI unit. We live with a mixed system. And how do we pronounce 1 Ma ? If you are french ...
hillwalker's user avatar

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