Playing with Sun Burn

One of my resolutions (I forget which) is to play with physics - this was supposed to encourage me to do cutting edge astrophysics research rather than spending all my time messing about with astronomical data analysis, but instead it's turning out to mean something different (and perhaps just as much fun!).

I discovered a program today for calculating the elevations of astronomical objects - I needed it because I had to work out when during the night of June 29th our Keck targets would be visible. If the elevation is too low, the light is too heavily absorbed by the atmosphere (the "airmass" is too high) and so the object is too dim to observe.

This reminded me of a problem I was thinking about while getting sunburnt on a boat last summer: I claimed that it was unnecessary to put on sun cream at 4pm because the decreasing elevation of the Sun meant that the time to get sunburn was increasing exponentially fast. Well, now I have the plot that shows this to indeed be the case! I used the astronomy program to work out the airmass towards the Sun throughout the day in Palo Alto on 20th June 2006, and then calculated the time taken to absorb the same amount of energy as you would in 10 minutes (a typical burntime) at noon, as a function of the time of day. That's what the plot at the top of this post is.

You can see that at 4pm (240 minutes past noon) the burn time is still only a quarter of an hour but is climbing: by 5pm the burn time is about 25 minutes, and at 6pm it is much longer than the remaining daylight time (even though the Sun does not set until 8:30pm) and we are out of danger.

This does remind me that I must put cream on early though: by 9:30am the burn time is already only 18 minutes. All of this stuff has been confirmed experimentally of course - ouch.

I May yet amount to something

This has been a turnaround month for me. Resolutions 1 and 3 came into alignment, eclipsing most others, though I've tried.

Coming to a pit of despair, staring down it and breathing in the fumes, I came to a realisation sometime in late April/early May: I should be teaching for a living.

I agree with Phil (see below) that teaching is a rewarding and challenging career, and I've decided it'll beat the hell out of rotting my brain at a computer in an industry I don't admire nor want to progress in. So.

Lucy wangled me a place at interview for the last remaining gap on the PGCE History course at Bristol Uni, the Thomas magic worked its charms, and I'm starting in September...

Good luck me.

As for eating well, and looking after the back, these have been pressed to the margins recently with the pressure of two other commitments. One is some freelance writing work, so appeasing Resolution 2, the other is playing the role of Paul Bratter in Barefoot in the Park:



But I think I can be forgiven for finally solving Resolution 3 once and for all. Well, at least until the little B*st*rds obliterate my confidence and I quit to become a desk monkey again.

Richard.

Black Holes for 4th Graders

New Year's Resolution 10: further the public understanding of science (originally suggested by Jack 2 years ago). Well, here are some members of the public, the 4th grade class of Orion Elementary School, Redwood City, and that's me explaining to them that 1) black holes curve space in the same way that this bowling ball is curving my table cloth, so that light (like that marble) no longer travels in straight lines, and 2) astrophysicists like to build models of the Universe and then play with them. Steven, Teddy and I spent the morning with them - they had a *lot* of questions and it was a lot of fun. Teachers do, I think, an enviable job. Our exploits did not go unnoticed - I am now signed up to lead the SLAC Kids' Day in August (inbetween UK trips...)