12
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 Geophysics.
The complex dynamical structure of reversals is supported by
sedimentary and volcanic records. Provided that resolution is
adequate, the ...
10
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 a while ago when enunciating his Third Law of Planetary Motion. There are many ways to write a formula to calculate Earth's speed around the Sun. But for your ...
8
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 timezones are divided in the pacific there are timezones that practically use the same time (e.g. UTC+12 and UTC-12), but are actually in two different days. However ...
5
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, not necessarily age and not necessarily measured from the present time.
examples
The fossil is dated to 110±2 Ma.
According to zircon dating, the granite ...
5
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 length everywhere on the planet. This is simply down to geometry.
However, the effects of astronomical seasons vary geographically in a number of ways. The ...
5
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 time and date of the earthquake(s). The USGS can create a similar data-set (try there). I used that to extract the earthquakes of magnitude 2.5+ in the SF area ...
5
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 forward for the answer in bold font after the figure, and come back here for the explanation.
Time zones are defined by by man just to facilitate time keeping. ...
5
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 physics and having a time standard that stays in sync with the Earth's rotation are at odds with one another. One solution is to continue to do what we do now.
The ...
4
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 Years or more to complete the time it takes is very variable.
After years with a weak and sometimes variable magnetic field. The magnetic field re emerges in ...
4
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 saying
obsidian as opposed to basalt
...you're comparing apples and oranges. So instead of discussing obsidian versus basalt, let's discuss phaneritic versus ...
4
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 it would take a humongous time to compute way beyond the capability of current computers. We published a paper back in 2014 where we talk about the role of ...
4
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 within sunrise and sunset.
I personally wouldn't consider that the dividing line between night and day. I consider night to be the period between dusk and dawn ...
3
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 because of the gravitation of other planets. These effects are minor, but enough that measuring units of years is tricky. So an annum is defined as 31,557,600 ...
2
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 years.
Also, both the Julian & Gregorian calendars were established centuries before the prime meridian was set in the 19th century. The formula for adding ...
2
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 time like that. A drive from the Appalachians to the East Coast would get you everything but the Archaean rocks, although the only Proterozoic rocks would be found ...
2
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 little or no change in time zone no matter how long you fly for.
At the other extreme, if you fly from east to west the time zones will go in the wrong ...
1
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 behind the UK, for Hawaii, Cook Islands & the Aleutian Islands.
1
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, is not the year our calendars use. That year is the tropical year. The sidereal year is the time it takes for the Earth to complete one orbit around the sun (...
1
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.
1
Your maths is not detailed, but you have the correct answer.
The Earth rotates at 15 degrees per hour (360 degrees/24 hours).
The time required to rotate 10 degrees is 10/15 = 0.666 hours, which is 40 minutes.
1
There are two issues (and one optimization) with/for the code above:
Array indexing starts with 0 (not 1) in Python. Therefore, it should be if data[0,m] == countries[i,j]: because you are interested in the first row;
m goes from 0 to 1 (for m in xrange(0,1):) but it should go from 0 to number_of_countries so that all columns of the energy are iterated.
...
1
Communisty has done a good job of giving the winners in various categories, but I think it's also worth mentioning the runner-up UTC+12:45, which is only used by the Chatham Islands, population 600. But UTC-12:00 beats this one, unless there happen to be enough ships in UTC-12:00 to furnish more than 600 people. And UTC+10:30 with 382 people seems ...
1
I don't know the book and the quality of fiction are rarely in the facts. However, it is always nice to think about the spinning of our planet and how our theories and methods relate to the actual astronomic observations.
Historically there have been a number of prime meridians, sometimes used simultaneously and sometimes to large confusion. However, what ...
1
To give a fuller explanation, the current calendar is the Gregorian calendar, which was introduced in 1582 to address the inaccuracies of the older Julian calendar. The Julian calendar gains a day every 128 years because the year is 365 with a leap day every 4 years for an average of 365.25 days long (the actual year is 365.24217 mean solar days). By the ...
Only top voted, non community-wiki answers of a minimum length are eligible
