Archive for August 7th, 2009

Brahe had a Sponsor. Kepler Works.

Bad Astronomy: Kepler works!

The bottom plot is the same thing but zoomed in to see more detail. That second dip is a lot more obvious. It’s not another planet blocking starlight, which is what you might first guess. It’s actually the light from the planet being blocked by the star!

The planet is reflecting light from the star, just like the Moon reflects sunlight, allowing us to see it. When the planet passes behind the star, we don’t see that light anymore, so the total light from the system drops a wee bit. It’s not much, and totally impossible to see from the ground, but Kepler was able to spot it. And that’s critical, because it turns out this dip is about the same thing we’d expect to see if a planet the size of the Earth were to pass in front of the star. In other words, the drop in light from a giant planet going behind its star is about the same as we’d expect from a smaller planet passing in front of the star.

The fact that Kepler spied this dip at all means that, if somewhere out there an Earthlike world is orbiting a star, Kepler will be able to detect it!


This is pretty cool.

Someone Divided By Zero

flickr: Maelstrom #3 -Kauai, Hawaii

This awesome photo is from the Mokolea Lava Pools, after a wave had hit and the water was draining. The post title is one of the comments. There’s a still-quite-cool “before” picture, too.

Death to Exponential Growth

Your body wasn’t built to last: a lesson from human mortality rates

What do you think are the odds that you will die during the next year? Try to put a number to it — 1 in 100? 1 in 10,000? Whatever it is, it will be twice as large 8 years from now.

This startling fact was first noticed by the British actuary Benjamin Gompertz in 1825 and is now called the “Gompertz Law of human mortality.” Your probability of dying during a given year doubles every 8 years. For me, a 25-year-old American, the probability of dying during the next year is a fairly miniscule 0.03% — about 1 in 3,000. When I’m 33 it will be about 1 in 1,500, when I’m 42 it will be about 1 in 750, and so on. By the time I reach age 100 (and I do plan on it) the probability of living to 101 will only be about 50%. This is seriously fast growth — my mortality rate is increasing exponentially with age.

It's a Small World, After All

The Size Of Our World

Looking from human perspective Earth may appear as an enormous object, a HUGE rock we’re living on. In space measurements, the size of our planet is infinite small. This comparison between Earth and “most popular” planets and stars really adds a new twist to the whole story.