• Today, 02:43 AM
I have a large collection of vinyl LP records going back over 65 years, along with some 78s going back 80 years or more. I am happy that there is a...
3538 replies | 499104 view(s)
• Today, 12:42 AM
I'm sorry, but two of my pet peeves are the Drake Equation and the Fermi Paradox, because of the what-ifs. As for the latter, let me say that Enrico...
2 replies | 62 view(s)
• Yesterday, 07:57 PM
Addendum to previous post: The refractive characteristics I illustrated are approximations that are excellent for thin lenses, long focal ratios and...
21 replies | 326 view(s)
• Yesterday, 07:49 PM
I will take up where George left off on the sketches. Sketch A: The vertical line between the lenses is their mutual focal plane. The source is a...
21 replies | 326 view(s)
• Yesterday, 05:00 PM
If the star is on the ecliptic, the parallax motion will be back and forth along that line instead of around an ellipse. If the proper motion is...
13 replies | 258 view(s)
• 2018-Jun-22, 05:11 PM
My bold. That depends on what you mean by "well enough." My hypothetical example, or one with a 10-inch focal length positive lens 10 inches...
21 replies | 326 view(s)
• 2018-Jun-22, 01:14 PM
Upon doing some relatively simple thought-exercise ray tracing, I have concluded that it will not work. Suppose we wish to concentrate the incident...
21 replies | 326 view(s)
• 2018-Jun-21, 11:11 PM
My bold. No, it doesn't matter how fast the proper motion is, provided you can keep it in the same field of reference stars for several exposures. ...
13 replies | 258 view(s)
• 2018-Jun-21, 05:26 PM
When I was in college we did a computer programming exercise using matrix techniques to disentangle the sinusoidal parallax from the linear proper...
13 replies | 258 view(s)
• 2018-Jun-16, 11:59 AM
If by gas clouds you mean the dense clumps which are visible if illuminated by embedded or nearby stars, I have no easy means of finding out how many...
34 replies | 844 view(s)
• 2018-Jun-16, 05:15 AM
My bold. Yes, lots of them, including such things as the Orion nebula. It and other such nebulae are dense concentrations, with more rarefied gas...
34 replies | 844 view(s)
• 2018-Jun-15, 05:08 PM
A word to the wise for Dave Lee and everyone else: Make sure you do not let bad popular media writing about black holes mislead you into thinking...
34 replies | 844 view(s)
• 2018-Jun-15, 05:03 PM
As I think I understand it, the lead isotopes are radioactive decay end products from uranium and thorium that were present when the material...
9 replies | 218 view(s)
• 2018-Jun-14, 11:15 PM
Yes, there will be mutual perturbations, just as our planets perturb each other as they orbit the Sun. The supermassive black hole is overwhelmingly...
34 replies | 844 view(s)
• 2018-Jun-14, 08:45 PM
The supermassive black hole at the center only eats stuff that blunders into the radius of no escape, which is only a few million miles in this case....
34 replies | 844 view(s)
• 2018-Jun-14, 01:15 PM
As has been said before, the Earth is not hot enough inside to induce a significant amount of exothermic fusion of light elements, and never has...
36 replies | 1621 view(s)
• 2018-Jun-14, 01:07 PM
It would have to stay behind the Sun. That means being in Earth's orbit, but 180 degrees around from Earth. That is the Lagrangian L3 point. It is...
8 replies | 495 view(s)
• 2018-Jun-13, 12:47 PM
Chlorine bleach straight from the bottle gave me upper respiratory irritation when I used it to clean mildew from my shower without adequate...
35 replies | 945 view(s)
• 2018-Jun-12, 12:41 AM
The light is deflected as it goes by a massive object.
24 replies | 827 view(s)
• 2018-Jun-11, 10:22 PM
If I spilled some dilute sulfuric acid, I could pour a suitable alkaline solution on it and then mop it up when it stops fizzing. Spilled...
35 replies | 945 view(s)
• 2018-Jun-11, 10:02 PM
My bold. I would not necessarily think that way. Let us start with Newton's equations. f =GMm/r^2 If we let m = 0, of course f goes to zero. ...
24 replies | 827 view(s)
• 2018-Jun-11, 12:54 PM
It appears that some of the subdivisions here have become redundant since the merger and subsequent evolution of the forum. Google Hangouts is a...
9 replies | 457 view(s)
• 2018-Jun-10, 01:21 PM
Apparently that dude was ignorant of the fact that there is person to person variation in the sensitivity curves of the cones, not to mention the...
25 replies | 617 view(s)
• 2018-Jun-10, 01:15 PM
This is beside the point with respect to the OP and the Wiki article BigDon referred to. The gas chamber was presumably operated by qualified...
35 replies | 945 view(s)
• 2018-Jun-08, 06:25 PM
The answer about existence depends on whether we define "sound" as the qualia in question or as the waves that stimulate it. Philosophers and...
25 replies | 617 view(s)
• 2018-Jun-08, 11:58 AM
That Hubble "tuning fork" diagram is based on an old galaxy evolution theory which has long since been superceded. If I am not mistaken, the...
43 replies | 1561 view(s)
• 2018-Jun-04, 04:46 PM
Oops! My 70-year-old brain had a senior moment. I stand corrected on the crosswalks. The intersection has a full set of crosswalks all around. I...
3395 replies | 499566 view(s)
• 2018-Jun-04, 02:48 PM
One of my neighborhood streets crosses busy US Highway 29 at a light. The street is narrow and has a sidewalk on only one side, with a single...
3395 replies | 499566 view(s)
More Activity

### 3 Visitor Messages

1. You live right near me. So I did something I almost never do. I friended you.
2. Thanks for the Web Site! I read it tonight. I´m goning to read it again tomorrow though... getting tired! It was good! Tnks!
Showing Visitor Messages 1 to 3 of 3
About Hornblower

#### Basic Information

##### About Hornblower
Location:
Falls Church, VA (near Washington, DC)
Interests:
Music, astronomy, model railroading
Occupation:
Retired U.S. Army Bandsman

#### Statistics

Total Posts
8,084
Posts Per Day
1.96
Total Albums
1
Total Photos
1
##### Visitor Messages
Total Messages
3
Most Recent Message
2010-Jun-30 08:11 PM
Last Activity
Today 01:11 PM
Join Date
2007-Mar-06
Referrals
0