Posts by bdm

by bdm
06.02.2012, 04:39
Forum: Physics and Astronomy
Topic: LHC: God Particle may have been glimpsed
Replies: 13
Views: 4393

Re: LHC: God Particle may have been glimpsed

I am also having problems accessing the CM site with a "You have been banned from this forum." message on all pages that I try to access.
by bdm
06.02.2012, 02:28
Forum: Physics and Astronomy
Topic: Scents of other habitable planets?
Replies: 3
Views: 2841

Re: Scents of other habitable planets?

Foundation's Edge by Asimov mentions this theme.
by bdm
21.12.2011, 00:33
Forum: Physics and Astronomy
Topic: Calculating grazing transits
Replies: 0
Views: 2871

Calculating grazing transits

I've been using the VSOP87 theory to calculate transits, such as transits of Venus as seen from Earth. To detect a transit at the closest approach of a sun and planet, the method I use is to compute the sums of the radii of the sun and planet, and if it is less than their separation then a transit o...
by bdm
11.06.2010, 02:50
Forum: Physics and Astronomy
Topic: Newton's Method for solving the Equation of Kepler
Replies: 0
Views: 2220

Newton's Method for solving the Equation of Kepler

I'll begin with a brief explanation: The equation of Kepler is: E = M + e sin E It is used for computing the position of an object in its orbit. This equation is transcendental (has no inverse). To solve for E, various methods exist. One good method is Newton's method: E(i+1) = E(i) + (M + e sin E(i...
by bdm
28.11.2009, 01:47
Forum: Celestia Users
Topic: About the spam bots
Replies: 29
Views: 6321

Re: About the spam bots

Clicking the URL, immediately exhibits this commercial link under Signature: (message intentionally snipped before example link) Sorry to tell you this, but you've made a really bad blunder here by including the spam link in your example. Many spammers sign up to forums just to get links in their p...
by bdm
28.11.2009, 01:41
Forum: Celestia Users
Topic: About the spam bots
Replies: 29
Views: 6321

Re: About the spam bots

How I would do it: If moderator intervention is required before registration, include a field that the user must complete that asks the following question: why do you wish to be a member of this forum? It is a good Turing test because spambots will either ignore the field, or give canned responses t...
by bdm
26.11.2009, 11:28
Forum: Celestia Users
Topic: About the spam bots
Replies: 29
Views: 6321

Re: About the spam bots

This may also be ineffective against the trickier bots that add legit-looking posts (e.g., "Hi, I'm new") before editing spam links into their posts at a later time. Do not allow posts to be edited after a certain time, say 1 day to 1 week after posting. This will impact on those legitima...
by bdm
26.11.2009, 11:22
Forum: Celestia Users
Topic: About the spam bots
Replies: 29
Views: 6321

Re: About the spam bots

One thing we could do is to disallow new users who have less than a certain number of posts from posting hyperlinks. Won't work. All a user has to do is spam the forum with non-link posts until the magic number is reached, then they can start spamming their crud. A probationary period of a certain ...
by bdm
14.07.2009, 10:43
Forum: Bugs
Topic: "Replace" invalidates child objects
Replies: 14
Views: 5501

Re: "Replace" invalidates child objects

The red line is the ecliptic. There's no control to toggle it in the Windows version (and it's too late to add one for 1.6.0). I'm not sure why it's showing up. You can run this one line script to get rid of it: celestia:setrenderflags{ ecliptic = false } --Chris To expand on this a bit: To get thi...
by bdm
12.07.2009, 11:46
Forum: Celestia Users
Topic: Celestia 1.6.0 released
Replies: 41
Views: 14648

Re: Celestia 1.6.0 released

Celestia 1.6.0 displays the ecliptic as a red line. How can we toggle this off with the Windows version?
by bdm
06.07.2009, 11:05
Forum: Development
Topic: Binary Data Base with Supplementary Mass-Luminosity Relation
Replies: 5
Views: 3460

Re: Binary Data Base with Supplementary Mass-Luminosity Relation

t00fri wrote:Interesting, isn't it?
Oh, yes.
by bdm
05.07.2009, 04:04
Forum: Celestia Users
Topic: Celestia 1.6.0 RC 3
Replies: 38
Views: 11654

Re: Celestia 1.6.0 RC 3

I have found more spectroscopic binaries with incorrect brightnesses. Beta Arietis . Apparent magnitude of each component (Celestia): A=2.60, B=2.64. Apparent V magnitude ( SIMBAD ): 2.64. CCDM J21158+0515 . Apparent magnitude of each component (Celestia): A=3.92, B=3.92. Apparent V magnitude ( SIMB...
by bdm
05.07.2009, 01:00
Forum: Celestia Users
Topic: Celestia 1.6.0 RC 3
Replies: 38
Views: 11654

Re: Celestia 1.6.0 RC 3

If we would allow ourselves to correct individual entries on the basis of "I think" or "I suppose" type of arguments, we would soon loose any credibility among scientists and other serious users. That's why I was bringing it to the attention of others with better access to prima...
by bdm
04.07.2009, 12:58
Forum: Celestia Users
Topic: Celestia 1.6.0 RC 3
Replies: 38
Views: 11654

Re: Celestia 1.6.0 RC 3

A couple of data file flaws: * The brightnesses of the components for Capella are incorrect . They are given as 0.06 and 0.08, which would give an apparent brightness of -0.68. Capella is not that bright; 0.08 is the apparent magnitude of both components together. +++++++++++++++++++++++++++ Just i...
by bdm
04.07.2009, 03:06
Forum: Celestia Users
Topic: Celestia 1.6.0 RC 3
Replies: 38
Views: 11654

Re: Celestia 1.6.0 RC 3

A couple of data file flaws: * The brightnesses of the components for Capella are incorrect. They are given as 0.06 and 0.08, which would give an apparent brightness of -0.68. Capella is not that bright; 0.08 is the apparent magnitude of both components together. * There is a typo in starnames.dat: ...
by bdm
27.06.2009, 23:40
Forum: Petit Bistro Entropy
Topic: Swine Flu
Replies: 108
Views: 27314

Re: Swine Flu

Swine flu is attracting some attention in Australia at the moment. It has a foothold here as one of the seasonal flu varieties. It's making this winter's usual colds a bit more interesting than usual. The H1N1 strain (Swine flu) has claimed the lives of about five people in Australia so far, all in ...
by bdm
20.06.2009, 22:14
Forum: Physics and Astronomy
Topic: Betelgeuse is Shrinking
Replies: 29
Views: 8576

Re: Betelgeuse is Shrinking

But would it produce a black hole, or a neutron star? Betelgeuse is at the low end of the mass range for supernovae. Its fate will either be a supernova with a neutron star remnant, or it won't have enough mass to ignite the last stages of nuclear burning and will end up as a white dwarf with an un...
by bdm
20.06.2009, 22:10
Forum: Physics and Astronomy
Topic: Betelgeuse is Shrinking
Replies: 29
Views: 8576

Re: Betelgeuse is Shrinking

If a star is burning silicon, better hope that it doesn't choose to do it on a weekend. A star that starts burning silicon on a Friday goes foom by Monday.
by bdm
20.06.2009, 21:57
Forum: Physics and Astronomy
Topic: Planets bigger than their stars
Replies: 11
Views: 3758

Re: Planets bigger than their stars

ajtribick wrote:
However, planets around main-sequence stars are more interesting.
Why?
Because we live on one, of course.
by bdm
06.06.2009, 11:08
Forum: Physics and Astronomy
Topic: Planets bigger than their stars
Replies: 11
Views: 3758

Re: Planets bigger than their stars

ajtribick wrote:There are already the examples of the pulsar planets... neutron stars are tiny, so even a terrestrial planet would dwarf the star.
This is true. However, planets around main-sequence stars are more interesting.

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