567 reputation
111
bio website keith-s-thompson.github.com
location San Diego, CA
age 54
visits member for 10 months
seen 8 hours ago

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

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


Jul
11
comment What is the farthest point of light that is emitted by a torch?
In US English, a handheld battery-powered light is called a "flashlight"; the word "torch" usually refers to a more primitive burning light source.
Jul
11
comment What would happen if an ice cube is left in space?
In the Oort cloud, I don't think there's a whole lot of gas and other objects for it to pick up (though we probably don't have a good estimate for its density).
Jul
7
comment What's the likelihood of the existence of unknown elements in the Solar System?
Elements in the "island of stability" are expected to be relatively stable, compared to their neighbors. Quoting the Wikipedia article, "Specifically, they are expected to have radioactive decay half-lives of minutes or days, with "some optimists" expecting half-lives of millions of years." Even with half lives in the millions of years, there could still have gone through hundreds or thousands of half-lives over the history of the Solar System. Unless the optimists are underestimating their stability, there should be practically nothing left of them.
Jun
17
revised One year on the sun
Spelling, cleanup
Jun
16
suggested suggested edit on One year on the sun
Jun
16
revised One year on the sun
added 11 characters in body
Jun
16
answered One year on the sun
Jun
13
comment In 2016, the summer solstice will coincide with a full moon. How often does this happen?
@Bishop: The solstice is a single moment. For example, this year's summer solstice occurs at about 10:51 UTC on June 21.
Jun
13
comment In 2016, the summer solstice will coincide with a full moon. How often does this happen?
If you're talking about an exact coincidence, it virtually never happens. If you're willing to accept a two-week margin of error, it happens almost every year. The 400-year cycle is an artifact of the Gregorian calendar, which has no effect on when or how closely the solstice and the full moon coincide.
Jun
12
comment Using the Sun as a Gravitational Lens
That confirms the phenomenon (gravitational bending of light) that makes gravitational lensing possible, but it doesn't confirm that the Sun can be used as a gravitational lens to achieve better telescopic viewing. Eddington didn't get a better view of those stars than he would have gotten at night.
Jun
11
comment Using the Sun as a Gravitational Lens
You don't see stars during the day because the atmosphere scatters sunlight. To use the Sun as a gravitational lens, you'd have to be in deep space, about 50 billion miles away according to MycrofD's answer. Since that is, to put it mildly, well beyond the atmosphere, an observer at that point could mask out the Sun's light. Light from a distant object could be bent around the Sun and focused on the observer, appearing as a ring surrounding the Sun.
Jun
10
comment Which is really larger, Big Dipper or Small Dipper, in 3D
@Marc: That's debatable, but with a little more specificity (as I discussed in my comment) the question could have an unambiguous answer. You might not find it a particularly interesting question, but that's different from being meaningless.
Jun
9
awarded  Citizen Patrol
Jun
9
comment Which is really larger, Big Dipper or Small Dipper, in 3D
Then by all means downvote the question, or post a comment, or flag it if you think it doesn't belong here, or just ignore it. Answers are supposed to be answers.
Jun
9
comment Which is really larger, Big Dipper or Small Dipper, in 3D
You'll have to decide which stars to consider. Each constellation covers a defined region of the sky and extends all the way to the edge of the observable universe. Assuming you define a reasonable set of stars for each constellation (the ones forming the outline of the bear, or the ones that have been assigned names of the form Greek letter Ursa (Majoris|Minoris)), I seriously doubt that relativistic distortion of space is going to be significant.
Jun
2
comment Why do we not send diggers to Mars if we think there's underground water?
The InSight lander, due to be launched in 2016, includes a probe designed to burrow up to 5 meters below the surface -- but it's designed to measure heat flow, not water.
May
9
comment Can Mercury hit Earth or Mars in the next 5 billion years?
@Gerald: I think the "Mercury–Jupiter 1:1 resonance" is just wrong, or at least misleading, but I defer to someone who understand this better to fix it. There's no mention of a 1:1 reference in the New Scientist article. The current ratio of Jupiter's and Mercury's orbital periods is about 49.25. The paragraph itself doesn't describe a 1:1 resonance. Perhaps the idea is that there's a resonance of something other than their orbital periods, but that's extremely unclear.
May
7
comment Can Mercury hit Earth or Mars in the next 5 billion years?
@Gerald: It says they may "fall into sync"; that's not a 1:1 resonance.
May
7
comment Can Mercury hit Earth or Mars in the next 5 billion years?
The "1:1" refers to a common ratio of a body's orbital and rotational periods, in contrast with Mercury's actual ratio of 3:2. The article does not say anything about any kind of 1:1 resonance between Mercury and Jupiter; rather it discusses a possible interaction between Mercury and Jupiter.
May
6
comment Can impact craters on the moon act like giant radio telescopes?
Actually the Arecibo dish is spherical, not parabolic, because it's steered by moving the detector, not the dish. Reference: en.wikipedia.org/wiki/Arecibo_Observatory