Comments on: Followup: City lights from space

By: Physicsman

Physicsman — Fri, 20 May 2011 03:20:14 +0000

Caleb Jones:

Disclaimer: I haven’t checked any of this to see if its reasonable!

My guess is, you would need the precise mass and size of the host star and the precise period of brightness change to establish an orbital radius and velocity. Using the radius, velocity and the precise rise (dim) time from max bright to least bright you could establish an estimate for the diameter of the planet. Knowing this you could predicted the amount of dimming you would expect and compare it to observed. I would be amazed if it is even remotely possible for the nearest known exoplanet. I think your best bet would be, after having found an exoplanet with a known period, to point a radio telescope at it (much better sensitivity and resolution then optical) and see if you pick up a late night monologue in alienese.

Your best bet is SETI. That is if it was still on…

By: Caleb Jones

Caleb Jones — Thu, 19 May 2011 20:43:42 +0000

I have a genuine astronomy question.

I understand that one of the techniques to detect exoplanets is to measure the delta in luminescence of a star that occurs when a planet transits in front of it.

Is it possible to, through some other independent techniques, figure out the size of the planet? If so, could that data be compared against the luminescence delta to see if there is a significant mismatch? And if so, could that be used as a way to indicate that the exoplanet itself is emitting light which might indicate intelligent life and technology?

There are a few steps to this and lots of room for problems from the lack of precision in our instruments, but it seems like it might be possible.

Anyone have any insight on this?

By: Don

Don — Thu, 19 May 2011 07:19:33 +0000

If you like differential equations check out this video. It’s a prototype of an interface on an iPad that allows you to directly manipulate parameters and coefficients to generate plots. Very cool.

In order to bypass moderation, go to vimeo and look at video number 23839605. Just put the number after the slash in the dot com with a slash following. If you are searching for it, the title is “Interactive Exploration of a Dynamical System”.

By: Physicsman

Physicsman — Thu, 19 May 2011 05:48:06 +0000

I think another lesson after having tried Google Earth and seeing that numerous people in the thread beat me to it is that when you have a pool of educated followers cloud sourcing them can produce amazing results. I think in your next blog you should post some random equation and state that it is the ‘newly’ discovered equation unifying the four known forces but you not sure about the order of the terms.

By: Mark

Mark — Thu, 19 May 2011 01:52:09 +0000

I love wolfram alpha! It’s especially helpful for differential equations.

By: Ross

Ross — Wed, 18 May 2011 20:46:54 +0000

One of the necessary skills for an airplane pilot is the ability to match up what you see out the window to the map. The effect is basically the same, looking at the ground from an airplane at 6,000 feet is like looking at a map at a very shallow angle, 5-10 degrees. Shapes are distorted and more difficult to identify (the curve of a road, the outline of a lake), so I tend to look for intersections, edges, and discrete landmarks such as stadiums, bridges, water towers, and airports of course.

At night, the view is remarkably similar to the posted photo, just a different scale. The small dots of light would be individual street lights, and the large patch might be a shopping mall. The yellow areas on the aeronautical charts are supposed to depict the actual lighted areas at night (see http://www.skyvector.com)

By: JohnDoe

JohnDoe — Wed, 18 May 2011 20:29:33 +0000

Before the internetz, you couldn’t just upload a random picture of the sky and have it automatically identified and annotated, even if it was mirrored, scratched and vignetted, as astrometry.net now does at http://flickr.com/groups/astrometry

By: MartinM

MartinM — Wed, 18 May 2011 19:08:11 +0000

Imagine waking up, looking outside your window, and having no clue at all even what part of the Earth you’re seeing!

I’ve had mornings like that.

By: Jules Stoop

Jules Stoop — Wed, 18 May 2011 18:12:09 +0000

‘New computer’? (Not a new Mac?)

By: Mark

Mark — Wed, 18 May 2011 15:23:11 +0000

An astronaut friend of mine who flew with Story Musgrave said that Story could recognize most oceans and bodies of water by their _color_ and hue.