5,692 reputation
1733
bio website keith-s-thompson.github.com
location San Diego, CA
age 56
visits member for 3 years, 10 months
seen Aug 23 at 1:14

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

SOreadytohelp


Dec
15
comment Why can't you escape a black hole?
@Omar: Yes, but in pure Newtonian physics you could escape without ever reaching the surface escape velocity. It's impossible only because of relativistic effects.
Dec
15
comment Is There Reddening on Objects Other than the Moon Upon Entry into Earth's Umbra?
The Moon, during a lunar eclipse, is illuminated by light from all of Earth's sunrises and sunsets simultaneously; the ISS would be get sunlight only from one part of the limb. But yes, it should happen similarly. I just tried and failed to find photos.
Dec
13
comment The Sun as a gravitational lens
I wonder if Jupiter is massive enough to be a "useful" gravitation lens.
Dec
12
comment How long does it take for radio or light waves to travel from Earth to Jupiter, Saturn, Uranus, Neptune and Pluto?
The time varies over a range of about 16 minutes depending on the relative positions of Earth and the target planet in their orbits; Earth can be 8 light-minutes closer than the Sun is, or 8 light-minutes farther away. I don't have the numbers handy, but a close approximation can easily be determined by looking up the distance of each planet from the Sun and dividing by the speed of light.
Dec
11
comment How many Pluto sized planetoids have been discovered?
Suggestion: Add the IAU definitions of "planet" and "dwarf planet" to your answer.
Dec
9
comment How does space affect the human body (no space suit, no space craft)
@CamJackson: In a vacuum, water can either boil or freeze, depending on the temperature. It can't be in the liquid state at pressures below about 6 millibars (atmospheric pressure is 1000 millibars). The phase diagram of water shows the gory details.
Dec
8
answered How does space affect the human body (no space suit, no space craft)
Dec
7
comment Why can there be fire in space while there is no oxygen?
@PatrickRitchie: Edited.
Dec
1
comment What is the official difference between a planet and a dwarf planet?
Pluto's orbit crosses Neptune's only in the sense that it comes closer to the sun than Neptune does. Pluto's orbit is tilted enough that it never actually comes very close to Neptune. In fact, Pluto's closest approach to Uranus (11 AU) is closer than its closest approach to Neptune (17 AU) according to this Wikipedia article.
Nov
30
answered Why can there be fire in space while there is no oxygen?
Nov
30
asked How plausible is a subsurface ocean on Pluto?
Nov
30
comment 2012: Is there some astronomical event happening?
Correction, my comment was on this blog post (regarding Julian vs. Gregorian calendars).
Nov
25
comment Most accurate ways to find the average distance between stars in Milky way galaxy
How do you define "average distance"? The most straightforward definition is, I'm sure, not what you mean: the average distance between X and Y for each pair of stars X and Y in the galaxy. That would be some tens of thousands of light-years. Do you mean the average, over all stars in the galaxy, of the distance to that star's nearest neighbor (e.g., about 4.3 light-years for the Sun)? How do you handle multi-star systems? How do you define multi-star systems? How do you define "star"? And the core is going to skew the results quite a bit, as are clusters.
Nov
19
comment If neutrinos travel faster than light, how much lead time would we have over detecting supernovas?
Typos: Meanwhile, the core collapse and rebound emits energy in forms that are absorbed by the body of the star, causing it to heat up.
Nov
18
answered Why does the “Troll-Mobile” not work?
Nov
18
comment How does a mobile phone vibrate without any external force?
For those who want to Google it, it's "eccentric drive".
Nov
18
comment If neutrinos travel faster than light, how much lead time would we have over detecting supernovas?
(ran out of characters) The bulk of the star isn't significantly transparent at all. We don't see the light from the blast until most of the star is blown away -- which happens in a matter of a few minutes or hours.
Nov
18
comment If neutrinos travel faster than light, how much lead time would we have over detecting supernovas?
Is scattering really the answer? My understanding is that the core collapse is a quick event that generates a blortload of neutrinos; the neutrinos travel through the material of the star (and anything else in their path) and reach us without delay. Meanwhile, the core collapse and rebound emits energy in forms that's absorbed by the body of the star, causing it to head up. We don't see the visible light until that energy (1) reaches the surface of the star, causing it to glow more brightly, and/or (2) blows away most of the star's mass, exposing the bright core.
Nov
18
awarded  Nice Answer
Nov
18
answered How does a mobile phone vibrate without any external force?