Little Lessons from Astronomy

Fun facts learned as I finally caught up on my reading:

• To you little romantics: unfortunately when you pay to get a star named after you or a loved one it is usually through some "unscrupulous commercial firm." The money you pay for the service is real, but the star names are not, seeing as none of them are recognized by astronomers. Rather, as my text kindly suggests, if you want to be remembered by astronomy, make a donation to your local planetarium or science museum. (Isn't it romantic?)
• The change in seasons is due to the tilt of the earth as it rotates, not due to the change in distance from the earth to the sun. Though the distance does change, it only undergoes a 3% distance variation in an entire year, hardly enough to influence seasons (besides, if this were the case, the seasons would be the same in the northern and southern hemispheres...and that's just crazy talk).
• A year is approximately 365 1/4 days long, which is why the leap year was introduced. And who was it introduced by? Julius Caesar! (That one Roman guy who invented salad). Unfortunately his system would have only been good if a year was exactly 365 1/4 days long, which it is not. He was actually off by 11 minutes and 24 seconds, which adds up to 3 days every 4 centuries. We can't have that...but his astronomical advisers blew it off...that is, until the first day of spring was on March 11th (and Easter kept moving earlier, which the Roman Catholics weren't down with).
• So Pope Gregory XIII reformed the calendar by dropping 10 days (Oct 4th, 1582 was followed by Oct 15th, 1582). Caesar added Feb 29th to every year divisible by 4, but Pope Gregory decided that only years divided by 400 evenly should be leap years. And ta da! We have the Gregorian calendar! This is far closer to the true length of a tropical year (which is 365 days, 5 hours, 48 mins and 46 secs long or 365.2422 mean solar days), seeing as the Gregorian system assumes a year is 365.2425 mean solar days.
• Sirius is a character in Harry Potter -- the dog-man. Sirius is also a character in...the sky. He's a star. And guess what he helps make up? a DOG. (Draco is a constellation too, a dragon, the little fire-breathing punk...) And my professor is named Moody. No joke. I love Harry Potter.

That's all from the book of the universe today. I hope you feel enlightened (the next chapter is on light...).