It’s all about appearances, man.

Ivan.

PS, I’m back, reading the few items left over from early last year, that I missed while on holidays. Shame is, I also have to admit that I didn’t read any from April 2007 onwards, until last night. I’m working through them now, and slowly into the future, while also reading the latest from now.

I think it is going to take a while to catch-up.

Ivan.

I didn’t write anything interesting, though, just a pointer to this nice article. It translates to “Phil Plait wishes us all a happy perihelion. I’d like to join him, especially now that [a few posts earlier] I complained about the fact that New Year’s eve can’t be moved to anytime you like”.

“Phil Plait wishes us everything a beautiful perihel. I follow, after I weighted degrees about the Nichtverschiebbarkeit of Silvester, – celebrates beautifully!”

Hmmm, well that sure helps, eh?

I know that Phil gave a rather precise distance for perihelion and I find it interesting that the value was not simple to determine. The internet, of course, offers many opinions, but this type of measurement should be known and published (as by NASA) as an accurate number. With such precision, by the way, is the distance between the Earth and Sun from surface to surface? Or center to center? Only curiosity makes me ask as I don’t think it will affect me much either way….

Also, does the speed of the Earth vary much from perihelion to aphelion? Do we speed up as we descend in orbit with a gradual slowing as we move further out? Or is it the opposite, so that we maintain roughly the same progress in degrees as we move to a longer orbital arc?

Either way, the roller coaster analogy does clearly explain my continuing dizziness and light-headed feeling that I experience every year around this time!!

.UNUSUALLY HOT WEATHER HAS ENTERED THE REGION FOR DECEMBER…AS THE EARTH HAS LEFT ITS ORBIT AND IS HURLING TOWARDS THE SUN

The top of the statement was labeled “..TEST…TEST…TEST…”, and its authorship was attributed to “HEINLEIN”. But obviously somebody didn’t have a sense of humor: the warning was gone when I tried to call it up again to show coworkers. Fortunately, I had printed it out, and it’s now in my Funny File

If I remember correctly, you took German in school. If jstarek.de cannot or will not write in English, then how about translating his comments. I would like to know what he/she has to say. [Of course, I am assuming it is German.]

Or maybe one of your bloggers can help out.

BA Mom

So the sun gets bigger in the winter? Where does the extra mass come from – or does the density go down?

tsk-tsk-tsk I though this site was about correcting misconceptions.

No kidding. All that’s left is for somebody to bring up Special Relativity and the fact that there is no universal “now”.

D’oh!

No, no, no! GMT does not have time zones (except in some rather misleading Microsoft software). Some countries (e.g., at the western end of North Africa) use GMT all year. Other countries (e..g, the United Kingdom) use GMT in the winter and in summer use GMT+1 called whatever locally (BST – British Summer Time, in the UK). GMT itself stays put all year round.

Lorne, is the “polar motion” you quote simply small-scale wobble about the pole? IIRC, that’s the effect of geologic-scale movements of mass, both crust plates and deeper magma flows, right?

“In 1928 the term Universal Time was adopted internationally as a more precise term than Greenwich Mean Time, because the GMT could refer to either an astronomical day starting at noon or a civil day starting at midnight. However, the term Greenwich Mean Time persists in common usage to this day in reference to civil timekeeping.”

“There are several versions of Universal Time:

UT0 is Universal Time determined at an observatory by observing the diurnal motion of stars or extragalactic radio sources, and also from ranging observations of the Moon and artificial Earth satellites. It is uncorrected for the displacement of Earth’s geographic pole from its rotational pole. This displacement, called polar motion, causes the geographic position of any place on Earth to vary by several metres, and different observatories will find a different value for UT0 at the same moment. It is thus not, strictly speaking, Universal.”

“UT1 is the principal form of Universal Time. It is computed from the raw observed UT0 by correcting UT0 for the effect of polar motion on the longitude of the observing site. UT1 is the same everywhere on Earth, and is proportional to the true rotation angle of the Earth with respect to a fixed frame of reference.”

“UTC (Coordinated Universal Time) is an atomic timescale that approximates UT1. It is the international standard on which civil time is based.”

So strictly speaking, when somebody talks about such-and-such a thing happening at 20:00 Universal Time, it’s UTC that they’re talking about. For most folks, this is the same as GMT, and is sometimes also called Zulu time (which refers to the nautical time zone containing the prime meridian).

Lorne
http://geekcounterpoint.net

Is it the same as GMT?”

For all practical purposes, yes!

I wonder if there are some that try to see if the sun triggers earthquakes and volcanic eruptions, just as they do with the moon. I wouldn’t put it past them.

Anyway, happy perihelion day to all!