814 reputation
312
bio website keith-s-thompson.github.com
location San Diego, CA
age 55
visits member for 1 year, 6 months
seen 2 days ago

I'm a programmer and all-around nerd living in San Diego, California.
I work at JetHead Development Inc.

E-mail: Keith.S.Thompson@gmail.com


Mar
24
comment Why there is no smoke around the Sun?
Related: physics.stackexchange.com/q/26628/5646
Mar
20
revised How rare are earth-like solar eclipses?
added 145 characters in body
Mar
20
answered How rare are earth-like solar eclipses?
Mar
19
comment Shadows of Light = Space or Dark Matter?
Shadows (since they're not material objects) certainly can travel faster than light. Consider a light source at position 0, an object 1 foot away (1 light-nanosecond) casting a shadow, and a wall 100 feet away. Move the object laterally at 0.1c. It will take 100 nanoseconds for the shadow to start moving, but it will then move at 10c. Set up the angles right, and it can move infinitely fast. A shadow is not a rod or a pair of scissors.
Mar
9
comment What is the term for astronomical objects outside the solar system that are smaller than dwarf planets?
@Kyth'Py1k: Perhaps that's just because all known asteroids are within the Solar System (unless I've missed some recent discovery). I have little doubt that if we discovered an asteroid-like (or planet-like) object orbiting, say, Alpha Centauri A, we'd call it an asteroid (or planet), Wikipedia notwithstanding.
Feb
27
comment When will a day on Earth & Mars be the same length?
And we'll need nearly two leap seconds per minute. The IERS will be very busy.
Feb
25
comment When we see the Sun, do we actually see its past?
In fact we see everything in the past, whether it's in space or not. If you see an object, say, 30 cm (~ 12 inches) away, you're seeing the light that left it about 1 nanosecond ago. At that scale, though, the delay in your own visual processing is much longer than the speed-of-light lag.
Feb
24
comment Temperature of the Sun's rays
Strictly speaking light doesn't have a temperature.
Feb
24
comment Why would a star’s position in the sky change relative to another star right next to it?
Is this something you've actually observed? If so, please update your question with the details.
Feb
18
comment What significance does coincidence or luck have in astronomy?
To address some but not all of your examples: A more nearly circular orbit for Mars might have delayed the discovery of Kepler's laws, but Mercury for example has a far more eccentric orbit. We have good views of many other galaxies, even with the telescopes available to Hubble. The first Mars flyby was only 6 years after the first Lunar flyby; a missing Moon would probably have slowed down our space program's but perhaps not by that much. Yes, it's very likely that astronomy is missing something very important. That's why we keep doing it.
Feb
17
comment Why are all quasars so far away?
But observations of quasar distributions could be illuminating. If nearby quasars are rare because old quasars are rare, the region of rarity should be roughly a sphere centered on us; if it's random, it's more likely to be some other shape, and there could well be other regions with few quasars.
Feb
17
comment Why are all quasars so far away?
You suggest that our region of space coincidentally happens to have fewer quasars and so is more hospitable to life. That would imply that other regions of space will have more quasars than our local region does when observed at the same cosmological epoch. An interesting idea, but not yet verifiable, since assuming the Big Bang was 13.8 billion years ago, we simply can't see regions of space that are more than 12.8 billion years old unless they're within 1 billion light-years.
Feb
15
comment Is Sun a part of a binary system?
The wobble would be periodic, but not annual. The period would be that of the two stars' orbit around each other. That period would have to be at least several centuries.
Feb
12
comment What astronomical observations would give conclusive proof of alien life?
(I tried and failed to move this to chat.) Why do think more references are needed, and why are you taking this personally? You've even acknowledged that I'm right. What more do you need?
Feb
12
comment What astronomical observations would give conclusive proof of alien life?
@Py-ser: Frankly, I don't think any more references are necessary.
Feb
12
comment What astronomical observations would give conclusive proof of alien life?
@Py-ser: I've never seen the word "exoplanets" used to refer to "exotic planets". As far as I know, exotic planets are just called "exotic planets". There's an "exoplanet" tag for this site; its description says "Planets that lie outside our solar system." The "exo-" prefix is quite common, and the word "exoplanet" has a well established definition.
Feb
12
comment What astronomical observations would give conclusive proof of alien life?
@Py-ser: As far as I know, "extrasolar planets" and "exoplanets" are synonymous (and a quick Google search for "exoplanet" tends to confirm that).
Feb
11
comment Why there are other planets in our solar system?
I'm voting to put this question on hold. There seem to be two very different questions being asked: (1) Why do other planets exist (which I suggest is off-topic; it might be a better fit for philosophy.stackexchange.com or one of the sites that deal with religion); and (2) What effect do other planets have on us here on Earth (which would be a valid question for this site).
Feb
11
comment Heat from other Stars
@WayfaringStranger: There's also enough energy to trigger the cells in my retinas.
Feb
10
comment How are parachutes usable in other places than Earth?
Also: en.wikipedia.org/wiki/Huygens_(spacecraft)#Parachute