Discussion on:

Geek Trivia: 21 years cold

Hi Jay,
I enjoy your posts a lot. And the Quibbles as well.
In your "21 years cold", you say: "In the Northern hemisphere, this heralds the official start of spring, whilst antipodeans in the Southern hemisphere get started with autumn."
I found surprising the use of "antipodeans" as those who live in the other Earth's hemisphere.
Technicaly talking, for geographers, "antipode" is the exact place in the diametrically opposite side of the Earth's globe. It's a point, and not a continent (despite of the very british "Antipodes" denomination for Australia and New Zealand), or the whole hemisphere. You'll find y nice and clear definition in Wikipedia: http://en.wikipedia.org/wiki/Antipodes
In this article you'll find also a nice paradox: The true "antipodians" are really rare. As most of the Earth's surface is covered by water, the "dry" places in the Earth with a "dry" antipode are not so frequent at all. The term "antipodian" refers better to fishes than people...
You can say it is a kind of broad or poetical meaning. I can accept it. After all, I like imaginative literature.

Best regards,
Ra?l

Hi raul62:
I think you meant "subtle" instead of "subtile".

Best,
John

You're right, John.

You don't have a counterpart.

When you say Mercury has a day that lasts 1.5 Mercurial years, does this mean it goes around the sun 1.5 times before it rotates 360 degrees? Fascinating. So how long is a Mercurial month? :o]

Hi Jay,

Thanks for another great astronomy-related article. I agree with everything you said, but you failed to mention one significant factor which affects the length of our day. That factor is atmospheric refraction.

Atmospheric refraction, caused by the varying densities of air within of our atmosphere (more dense down low and less dense up high), causes light from the Sun to be bent toward the Earth. This lensing effect allows us to see the Sun for a few minutes after it has actually passed below our horizon in the evening, and also before it has risen above our horizon in the morning.

Happy vernal equinox!

Larry

"Uranus is tilted"--sounds like the punchline to a joke!

The tilt of the earth putting the northern hemisphere closer to the sun isn't the real cause for the warming of the seaasons. The tilt just makes it so the radiation from the sun has less atmosphere to battle through so it is more efficient at warming our hemisphere. The earth is closest to the sun in December. This surprises a lot of folks that think summer is when we are closer to the sun, but then they are forgetting about the folks in Australia.

The meteorological seasons are determined by temperature, and don't lag behind their "scheduled" arrivals, but occur prior to them, on the first of the month.
Wikipedia describes it well in the section on "season": "So, in meteorology for the Northern hemisphere: spring begins on March 1, summer on June 1, autumn on September 1, and winter on December 1. Conversely, for the Southern hemisphere: summer begins on December 1, autumn on March 1, winter on June 1, and spring on September 1."

THE DATES HAVE BEEN HANDED DOWN THRU RECORDED HISTORY

FIRST DAY OF SPRING IS HAS AND ALWAYS SHALL BE MARCH 21

JUST CHANGING THEM ON A CALENDAR DOESNT MAKE IT SO