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spartan45

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spartan45 last won the day on February 6 2018

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  1. As others have already stated the visible universe is finite and just does not have enough stars to light up all of the sky. I did wonder if dust clouds between the stars might be absorbing a lot of the starlight so it wouldn't shine through to us. But apparently scientists tell us that the dust itself would absorb so much energy from the starlight that eventually it would glow as hot and bright as the stars themselves. So I guess dust the dust cloud idea is a non-starter. For a good comprehensive answer to this post’s question, I recommend the reference below. https://spacepla
  2. TomBooth; thank you for posting this interesting topic, very brave of you to challenge both the second law of thermodynamics heat flow statement: ‘Heat flows spontaneously from a substance at a higher temperature to a substance at a lower temperature and does not flow spontaneously in the reverse direction’ and also Carnot’s principle, (An alternative statement of the second law of thermodynamics), ‘No irreversible engine operating between two reservoirs at constant temperatures can have a greater efficiency than a reversible engine operating between the same temperatures. Furthermore, all rev
  3. I appreciate the Sun is a star. I must admit the question and wording ‘at what altitude can stars been seen in daylight?’ does seem a bit weird, but then so does the seemingly black void witnessed by astronauts and visual spectrum cameras above the Earth’s atmosphere from spacecraft and the International Space Station when the Sun is not blocked by the Earth. I am now curious how the Hubble Space Telescope overcomes the problem of seeing stars (other than the Sun which it must not look at because it is so bright it would destroy its sensitive instrumentation) in daylight, all I can think of is
  4. The existence of the Hubble Space Telescope is used as proof that stars can be seen in daylight above the atmosphere. The Hubble ST uses 3 spectral ranges, the near-UV (pivoted at 300nm), Visual light (380nm-740nm) and a limited infra-red (800nm-2500nm) capability. Here’s the thing; can the Hubble ST see stars in daylight using the normal human visual light spectral range (380nm-740nm), or does it have to resort to using the near-ultra violet spectral range ( pivoted at 300nm) to see stars in daylight? The only other optical space telescope I’m aware of is the Chang’e 3 Lunar-based ultraviol
  5. Special relativity means moving clocks run slow. The challenge is which clock is moving, so I hope this experiment (Keating) carried out in the 70’s using an aircraft heading W and then repeating the procedure heading E, while carrying atomic clocks synchronised with a master atomic clock at an observatory in the United States helps make sense of it: The clock on the W bound aircraft was travelling against the East bound spin of the Earth, (rather like a person walking the wrong way along a conveyor and not moving very much), while the master atomic clock in the United States was moved faste
  6. It is my understanding that an additional chip was fitted to the power steering, before leaving the factories, to detect if there was any movement of the steering wheel whilst the car was moving. If there was none, it would put the car into ‘clean’ mode to cheat the rolling road emission test, reverting back to ‘dirty’ mode when it detected steering wheel movement at the end of the test. I was amazed at how simple, but effective, this method of foiling the world’s diesel car emissions regulations appears to have been. We need to be watchful.
  7. Does anyone know if an individual is allowed to describe how the emissions test was cheated?
  8. Uranium is in short supply on the Moon. Ref: https://www.space.com/8644-moon-map-shows-uranium-short-supply.html Thorium (Th) is plentiful at Mare Imbrium on the near side and on the Moon where the lander Chang’e 3 and its rover, Yutu (Jade Rabbit) landed (44.12 deg N, 19.51 deg W) on 14 December 2013. Thorium is also plentiful in the south-pole Aitken Basin region on the far side of the Moon within which lies the Von Karman crater where the lander Chang’e 4 and its rover Yutu 2 (Jade Rabbit 2) landed (44.8 deg S, 175.9 deg E) on 3 January 2019. Ref: http://www.planetary.org/blogs/emily-lakdaw
  9. True. Thank you for correcting me; indeed, it was not astrology.
  10. Apologies for posting this after OceanBreeze has answered so well but I’d already written it and I need clarification on the Doppler Red shift equation. Special relativity means moving clocks run slow. Alice’s clock is moving in respect to Bob’s clock on Earth. The time dilation equation is: ∆t0 = ∆t√ 1 – v2/c2 ∆t0 = Alice’s spacecraft time interval (in light years for this example) ∆t = Bob’s Earth based time interval in light years = 3/0.6 = 5 v = spacecraft velocity 0.6c c = speed of light (2.99792458x108 m/s) (3.0x108) rounded (Cancels out in this example) ∆t0 = ∆t√1 –
  11. I just noticed these posts of 2016 which I think are interesting. Is this an example of noble intentions to promote further education, (also see the titles of other papers then downloaded), while testing even my view that astrology is not fiction; below are extracts (two short sections of text) from: NBER WORKING PAPER SERIES SEASON OF BIRTH AND LATER OUTCOMES: OLD QUESTIONS, NEW ANSWERS Kasey Buckles Daniel M. Hungerman Working Paper 14573 http://www.nber.org/papers/w14573 NATIONAL BUREAU OF ECONOMIC RESEARCH 1050 Massachusetts Avenue Cambridge, MA 02138 December 2008 ‘We find that women g
  12. With reference to 8 April 2017 post above, low sunspot activity seems to cause pessimism, so markets fall. The various world financial falls are approximately in line with the low sun spot activity start point of October 2018: Ref: https://www.spaceweatherlive.com/en/solar-activity/solar-cycle There are many articles about world stock markets falling in October 2018: Ref: https://edition.cnn.com/2018/10/31/investing/stocks-markets-october/index.html Ref: https://www.marketwatch.com/story/why-the-dow-tumbled-600-points-and-the-nasdaq-fell-into-correction-territory-for-the-first-time-in-2-years-
  13. (1) No, I simply wanted to keep the question short. (2) Venus has an apparent magnitude of about -4.8, brighter than the estimated -2.2 of the sky as seen from the ground in daylight, so may be visible then. Jupiter is too close to the Sun and too dim at -1.74. Sirius -1.47, not present during daylight and too dim anyway, Mars 0.05, too dim. Except for the estimated -2.2 of the sky from ground level, apparent magnitude and relative position of the planets and star listed will vary with time and location so only valid 5th Dec 2018. Ref: https://www.timeanddate.com/astronomy/night/usa/jefferso
  14. Here is an interesting 1965 documentary ‘BBC Horizon, 1965 Man in Space’ The space race was about the halfway point. Interest in space exploration was intense and yet it appears no answer was found to what altitude can stars be seen in daylight because at about two minutes into the ‘BBC Horizon, 1965 Man in Space’ documentary Frank Borman states ‘During the daytime we were unable to see the stars, this confounds the scientist, but perhaps it was due to light scattering on our windows or perhaps it was due to the Earthlight reflection. We were unable to see the stars in the daytime.’ The int
  15. On 20th November 1984 a new legal entity was born in California called the SETI Institute. Its roots were Project Cyclops: A Design Study for a System of Detecting Extra-terrestrial Intelligence in 1971. A project to search for artificially generated radio signals from a distance of up to 1,000 light-years. SETI states ‘Our mission is to explore, understand, and explain the origin and nature of life in the universe, and to apply the knowledge gained to inspire and guide present and future generations. We have a passion for discovery, and for sharing knowledge as scientific ambassadors to the p
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