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Everything posted by Thomas

  1. Assuming that the small hand is the "Minutes of Arc" hand and that it makes one rotation for every ten minutes of arc, (explaining the numerals) then the angle displayed is, in my opinion, 119 degrees and 7 minutes. This is not accurate for 1:15 pm GMT on June 5th. The angle at that time should be very close to 90.
  2. It seems apparent to me that the dial to the right, showing 11, 12 and 13 has sufficient space for 36 numbers, presumably 0 to 35, and is showing tens of degrees. The hands, therefore show degrees and minutes of arc. It is unclear to me which hand is which. The puzzle is, in my opinion, why the "Minute of Arc" hand has numerals around the periphery of its dial. Unless these are decorative, it suggests that the clock has a dual function, that is presently not clear to me.
  3. The two lines are the Ecliptic and the Galactic Equator.
  4. The term, "lunar," is an adjective meaning, "pertinent to the Moon." It is not a name. Cruithne and the other numbered objects mentioned on the linked TV show orbit the Sun and not the Earth, so they are not moons of the Earth. They are asteroids that have an orbital resonance with the Earth. The BBC comedy department should not be regarded as an authoritative source for scientific information!
  5. Yes, George Ellery Hale did indeed discover that sunspots are a magnetic phenomenon, but I would doubt if this was accidental, since he was using a modified spectroheliograph known as a magnetograph.
  6. Actually, the energy of a photon is determined by multiplying the Planck Constant ( note the spelling ) by the speed of light, and dividing by the wavelength. E = h c / lambda .
  7. Post 3 states first, "Its because it is speeding up in its orbit." This is incorrect. As the moon recedes from Earth, its orbital speed must decrease, or it will break out of Earth orbit. Secondly, the stated reason is a, "tidal slingshot effect." This does not exist. Thirdly, it is stated that, "if there was no water on the earth it wouldn't move away." Again incorrect. The lack of water would make virtually no difference to the moon's orbital recession, since the amount of water is only a tiny fraction of the total mass of the Earth.
  8. It's disappointing to note that, despite a good answer to the initial question having been provided by the link in post 2, posts 3 & 5 subsequently gave answers that are utterly inaccurate.
  9. Unfortunately, you have miscalculated by a factor of a thousand. The motion of ten inches is only about 0.000002 degrees. This, however, is completely irrelevant, since the Earth's axis of rotation can be up to 45 feet from its mean position due to a couple of nutations. Furthermore the mean position is migrating at about 8 inches per year, in the direction, at the North pole, of approximately 80 degrees west.
  10. This video is actually quite misleading. It suggests that, as seen at the distance of the moon, Jupiter would virtually fill the sky. In fact, it would only subtend an angle of about 23 degrees.
  11. No, that's not how it works. Increasing the Earth's orbital velocity would push the Earth out of orbit or into an eccentric and possibly unstable orbit. Orbital velocity is the square root of GM/r . Therefore as radius increases, the velocity decreases by the inverse square. For example, Venus orbits at 35,000 m/s, Earth at just under 30,000 m/s and Mars at just over 24,000 m/s. The idea that placing an asteroid in front of the Earth would speed it up is laughable nonsense, since the mutual gravitational attraction would soon result in a collision.
  12. Edwin Hubble was certainly not the first astronomer to use a telescope for deep sky work. He, and his colleague Milton Humason, working at Mount Wilson, proved by using Cepheid Variables, that the so-called, "spiral nebulae," were actually galaxies in their own right, well beyond the Milky Way. They measured galactic red shifts, and established that the velocity of recession is linked to distance. The term, "Doppler Effect," is a, "Principle in Physics whereby the pitch of sound or the wavelength of light is altered by the velocity of the emitting object."
  13. The moon will never leave it's orbit around the Earth!
  14. I may be misreading, but I suspect that Sammy1404 is alleging that an object approaching the Earth cannot be seen by observers on Earth until after the object has arrived. If this is the case, then he is completely incorrect, since light from an approaching object will always precede the object, and the object will therefore be visible throughout it's approach.
  15. If the Andromeda Galaxy was about to hit our's, then it would (obviously) be much closer than the 2.2 or 2.9 million light years stated by Sammy, and the light emitted by it would reach us much quicker. We would therefore be able to watch it as it approaches.
  16. The arithmetic coincidence first noticed by Johann Titius, (note the spelling) and promoted by Johann Bode, predicts that Neptune orbits at 38.8 AU, but, in actual fact, Neptune is only at 30.1 AU. Barrie William Jones is therefore wrong.
  17. Unfortunately, it may well be a joke! Sir Isaac Newton remained unmarried and there is no record of him ever fathering children. He certainly claimed to have had none. Therefore, anyone claiming descendancy from him should be viewed with suspicion. Furthermore, he was born into a Church of England family, and his step-father was a minister of that church. Although his beliefs were often at variance with orthodox Church teachings, he remained in it all his life, and carried out a great deal of religious research.
  18. Steve makes a good point. On the intergalactic scale, our galaxy and M31 are not actually heading directly towards each other, rather, they are heading, on converging courses, in the direction of Leo. As far as the sun's galactic motion is concerned, it's orbit is taking it, very approximately, towards the Carina/Vela/Crux direction, at about 220 km/s. This orbit is elliptical and has a North/South oscillation, so I will not attempt to be too precise. However, with regard to the initial question, and bearing in mind the distances involved, my original response is accurate.
  19. The Sun, and therefore the entire solar system, is heading in the direction of a point on the border of Lyra and Hercules, at approximately RA 18Hrs 30 mins and Dec. 30 degrees north. This position, known as the solar apex, is about 10 degrees SSW of Vega, just east of the 4th magnitude star Omicron Herculis. The velocity is about 16km/s. This motion is independent of the galactic orbital motion.
  20. Yes, really! If the volcanism had been as a consequence of the heat caused by gravitational contraction, then it would have occurred during and immediately after the moon's formation. The resultant maria would therefore have suffered the same impact cratering as the rest of the lunar surface. The fact that the maria have relatively few craters demonstrates that they were created long after formation, and it follows that another heat source was the cause of the volcanism.
  21. I am surprised that no-one has mentioned Norton's Star Atlas and Reference Handbook, edited by Ian Ridpath and published by Longman, or Patrick Moore's Yearbook of Astronomy, published by McMillan. Both are very informative and interesting. Another marvellous reference book is The Astronomy Encyclopaedia, published by Mitchell Beazley. It has over 100 expert contributors, and was edited by P.Moore in 1987. I am not aware of any more recent editions, but the vast majority of it's content is perfectly accurate and relevant.
  22. The moon's volcanic period was approximately between 600 million and 1000 million years after it's formation 4500 million years ago. The volcanism was caused by heat generated by radioactive decay of some of the heavy elements in the lunar core. After about 2500 million years, the heating ceased and the Moon has since then been effectively a solid body, with the exception of the Regolithic surface overlying the crust.
  23. The lines you see on the lunar surface are referred to as, "rilles," and are the result of volcanic action. They can be either channels cut by flowing lava, or cracks due to the contraction of cooling lava. They are not the result of fluvial action since the Moon cannot sustain liquid water. The formation of the Rupes Recta was most likely as a result of the cooling of the Lunar Crust shortly after formation. The Moon does not have plate tectonics.
  24. Astronomy is beyond doubt a science. However, the purpose for which it is studied or practised, ( whether for research, education, exhibition or personal interest ) and the competency ( or lack thereof ) of the student or practitioner, are an entirely different matter.
  25. No, orbital velocity would have no effect on any tides that this planet's oceans (should they exist) may experience. Furthermore, if the planet is in captured rotation, and has no significant satellite, then it will have no tides.
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