Recent content by hipparchos

Sure, I understand why most physicists accept \LambdaCDM. A lot of work by a lot of people has gone into integrating DM, DE, & inflaton into the standard model. Meanwhile the "other side" only has a handful of people working on it, so I'm also not terribly surprised that similar grand...

Right. You've shown that by imagining that there's something there that we can't detect, we can "save the phenomena" (as Ptolemy would say). Sorta like an epicycle. It works, no doubt about it. But is it true? GR gravity is extremely well tested at solar system scales and below. At larger...

So, starting with the assumption that GR gravity is correct, you have proven GR gravity is correct. Got it. Or a different physics, which apparently was not tested by these authors. Let's put it this way: IF GR gravity is correct, THEN you need DM. That's obviously true and non-controversial...

And normal matter is ruled out because ... ?

I'll post it, because it's dynamite. http://www.scilogs.eu/en/blog/the-dark-matter-crisis/2012-04-19/dark-matter-gone-missing-in-many-places-a-crisis-of-modern-physics. And here's the discussed paper, which rules out a spherical DM halo in the Milky Way at the 4\sigma confidence level, using...

This is impossible to compute. Yarkovsky effects are basically impossible to compute for a single body, because it depends on mass, albedo, rotation rate, sphericity of the object, etc. -- most of which are only tentatively known for asteroids. Also the effect is very weak with the more massive...

Why? Why should DM behave any differently under gravitation than normal matter? This is a huge weakness for DM: it's a "just so" type of theory that behaves just the way you want it to behave so that everything works out right. If the galaxy is spinning too fast, no problem: there's more DM...

Perhaps you would care to supply a correction.

No. The Hubble's resolution is 0.05 arcsec, essentially the same as the apparent diameter of Betelgeuse.

No. But we can determine its diameter using interferometry.

Perhaps this is simpler: For an airless world, distance to the horizon is D = 3571.6 √h ... where D is the distance to the horizon in meters, and h is eye height in meters. For Earth with a standard atmosphere: D ≈ 3924.8 √h This distance (and the differences between atmosphere and...

Most common formulae for refraction break down at and below the horizon. Here's one that doesn't. For an object with a true (unrefracted) altitude H in degrees: compute v (in degrees) = H + (9.23 / (H + 4.59)) then refraction r in arcsec is : r = 58.7 * cos v / sin v and apparent altitude h...

For most purposes, I'm guessing an average would work almost as well: 23 hours, 37 minutes, 28.1 seconds.

The basic thought behind stellar classifications is that all stars start out as hydrogen, and that the major difference between types is the mass of the star. As a star ages, it advances in stages through burning hydrogen, helium, carbon, and heavier elements. As this happens, the spectrum of...

Probably not. Amateur equipment is designed for images, not spectra. Beyond that, getting a RV from a spectrum is tricky and generally gives low-precision results. Only in the past couple of decades have professional techniques emerged that have allowed high-precision RVs needed to detect planets.