Nasa / Space

Geek Trivia: 21 years cold

What planet in our solar system has the harshest winter, one that is measured in decades?

For those of you keeping score at home, a change in seasons is almost upon us, as the first equinox of 2008 occurs on Mar. 20 (or Mar. 19, if you're in the Mountain time zone or westward of this longitudinal marker). In the Northern hemisphere, this heralds the official start of spring, whilst antipodeans in the Southern hemisphere get started with autumn. You'll be pardoned, of course, for the traditional frustration if the actual weather outside your door pays absolutely no heed to the official seasonal shift.

This isn't a surprise, since the equinox has been a misnomer almost from the coining of the term. The etymology of equinox is Latin, from aequus, meaning equal, and nox, for night. Ostensibly, the word refers to a date when day and night are both precisely the same length, but on the equinox, the actual day is longer than the night. For that, you can blame astronomers.

One of the common astronomic connotations of equinox is a day where the sun spends an equal amount of time above and below the horizon. However, astronomers make these determinations from the center of the sun's visible disc, so even when the sun is "below" the horizon, a portion of its disc is still showing. On average, this makes the day 14 minutes longer than the night on the date of the equinox.

In strict astronomy terms, the equinox occurs when the sun directly aligns with the point in space where the Earth's equator lines up with the ecliptic plane of the solar system. As most of us learned in elementary school, the Earth tilts on its axis -- about 23.5 degrees -- so that the equator is never "flat" with the ecliptic. It is this tilt, and the fact that the Northern and Southern hemispheres incline closer or farther away from the sun as the Earth completes its yearly orbit, that create our seasons.

For those of us in the Northern hemisphere impatient with the meteorological arrival of spring lagging too far behind the scheduled arrival of spring, be thankful you don't reside on one of the other local planets -- some of which sport far more unforgiving axial tilts and seasonal variations. One planet in particular has an inclination so extreme, its winters are measured not in months or years, but decades.

WHAT PLANET IN OUR SOLAR SYSTEM HAS THE HARSHEST WINTER?

Get the answer.

About

Jay Garmon has a vast and terrifying knowledge of all things obscure, obtuse, and irrelevant. One day, he hopes to write science fiction, but for now he'll settle for something stranger -- amusing and abusing IT pros. Read his full profile. You can a...

15 comments
jlw2135
jlw2135

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

elhudman
elhudman

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."

boomchuck1
boomchuck1

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.

barksbruisers
barksbruisers

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

Larry,
Larry,

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

dolthead
dolthead

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]

raul62
raul62

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

ttlanhil
ttlanhil

Here in Australia, the 'official' start of the seasons corresponds to the meteorological seasons. Autumn has been in effect for almost three weeks now; although you wouldn't know it from the temperature, we've had a heat wave here in S.A. I believe it was 15-16 days of temperatures above 35C (95F in the old reckoning), with most of those days closer to 40C (104F)

Larry,
Larry,

I believe there is a new surgical procedure which can correct that physical anomaly now. It's worth it too, as the procedure eliminates potty problems, messy bathroom floors, ridicule in the showers at the gym, etc. Great post, BarksBruisers! I really needed a good laugh today! :o) Larry

dolthead
dolthead

Not to mention those of us who live up against towering Rocky Mountains, so the sun doesn't shine til well after "sunrise" and sets long before "sunset".

Dr. Tarr
Dr. Tarr

Wait a minute, Mercury doesn't have a moon, and therefore no month.

j1shalack
j1shalack

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

raul62
raul62

You're right, John.

Editor's Picks