1,587 reputation
bio website msquant.sourceforge.net
location Århus, Denmark
age 50
visits member for 5 years
seen Nov 22 at 10:04

(Last updated 2015-10-21.)

I am mostly interested in making scientifically important observations, like timing occultations of or by Solar System bodies and measuring variable stars.

I am also interested in citizen science projects and participate in some of them, like Galaxy Zoo.

I have been an amateur astronomer since 1975 and have worked at the European Space agency's (ESA) technical centre in Holland, ESTEC, on the ARISTOTELES mission, an earth gravity mapping mission.

Approximate coordinates: 55°20 N, 10°20 E


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Blog. Sample: Jump the shark.

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comment If dark matter only interacts with gravity, why doesn't it all clump together in a single point?
How is our galaxy held together then? Doesn't this require clumping of dark matter towards the center of the galaxy?
comment How does light speed up after coming out of a glass slab?
So sad! All incoming photons die :-) Isn't there a chance a small percentage will survive (say, when the glass is thin)? Could a finite-length beam of light have its intensity profile changed this way (e.g. some of the leading-edge photons are delayed and some not)?
comment Do solar systems typically spin in the same direction as their galaxy?
Re: "true of the galaxies in the solar system" Don't you mean it the other way around?
comment Why didn't the Big Bang create heavy elements?
So if all atoms in the universe started out of lead atoms, would they extremely quickly be split to elementary particles (before the universe could cool down sufficiently)?
comment If all motion is relative, how does light have a finite speed?
Re "All the interactions present in the universe do not propagate instantaneously". What about entanglement then?
comment Throwing a micro black hole into the sun: does it collapse into a black hole or does it result in a supernova?
Are the 7 significants digits warranted for the temperature and luminosity?
comment Is an H bomb a better “fusion reactor” than the Sun's core?
Despite the name, an H bomb is not really a fusion bomb, is it?
comment Why is the sky of the moon always dark?
How reflective is the surface (for instance, in relative terms compared to a desert on Earth)?
comment Why are electromagnetic waves called waves even though they don't travel through a medium?
Possible duplicate of Why don't electromagnetic waves require a medium?.
comment If the gravity at the center of the Earth is zero, why are heavy elements like iron there?
Where is that figure on Wikipedia?
comment Is there a maximum frames per second (FPS)?
That is a lot of frames!
comment Why do soap bubbles rise?
~4% CO2 seems a bit high (and the part of the Wikipedia article that claims it does not contain any sources). It might or might not be the number for a 20 seconds breathholding and is thus not representative.
comment How intense a magnetic field would it take to keep an hypothetical iron-made moon orbiting around it?
Wouldn't the potential energy in the magnetic system quickly be converted to heat due to hysteresis loses? Or is that only in ferrite materials or similar?
comment Why are sine/cosine always used to describe oscillations?
This is better than dancing hamsters :-)
comment How was this dot identified as a mystery planet originally (Pluto in this case)?
OK, this may not be too useful for the outer planets (Neptune is in retrograde motion 43% of the time), but couldn't the Earth's motion be compensated for?
comment How was this dot identified as a mystery planet originally (Pluto in this case)?
Unless near opposition (retrograde motion), the rate of apparent movement is an indication of how far out it is, right?
comment What is the irregularity in Uranus' orbit that is caused by Neptune?
"to affect where they are orbiting around a particular spacecraft". Don't you mean "to affect where they are orbiting around a particular planet"?
comment Does the Earth's rotation affect an object in the stratosphere?
I don't think removing the wind (presumably differential speed wrt. to the group below) from the equation is the same as removing the atmosphere (apparently whoosing by at 1256 km/h).
comment Can extra-solar gamma rays reach the Earth's surface?
The source states that the the window for indirect observations is 100 GeV to 50 TeV.
comment Can extra-solar gamma rays reach the Earth's surface?
Access to the book worked when I tried it today. From page 13: "The earth's atmosphere effectively blocks all electromagnetic radiation of energies greater than 10 eV. The total vertical thickness of atmosphere above sea level is 1030 g cm-2, and since the radiation length is 37.1 g cm-2, this amounts to more than 28 radiation lengths. This is true up to the energy of the highest known cosmic rays (some of which may be gamma rays)." This, I think, answers my question conclusively. May be included in the answer.