Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The Solar System's Second Sun

  1. Sep 7, 2014 #1
    Does anyone believe that the solar system has a second star? There is a theory that the solar system has a second, larger star called Nemesis. It has an oval shaped orbit around the sun, curving very close to the sun and then traveling 1 light year away, interrupting the asteroid belt surrounding our solar system, and sending a meteor straight at Earth. 1 orbit of Nemesis takes 26 million year, thus explaining why we get hit by a meteor every 26 million years.

    But the thing I don't understand is, when the last meteor hit, why did no one see a second, massive sun in the sky? Or why didn't the Earth become extremely hot as the sun passed?
  2. jcsd
  3. Sep 7, 2014 #2


    User Avatar

    Staff: Mentor

    What is your source? It is impossible to comment sensibly without knowing exactly what it is that you've heard.
  4. Sep 7, 2014 #3


    User Avatar
    Gold Member

    Wiki Article
    Last edited: Sep 7, 2014
  5. Sep 7, 2014 #4
    Yes I realise this is only a theory, and there is not much evidence to support it, but there is so much we don't know about the universe we live in, something like this could may well be true.
  6. Sep 7, 2014 #5


    User Avatar
    Science Advisor
    Gold Member

    If "we get hit my a meteor every 26 million years" because of Nemesis making a close approach, then the reason why no one saw a "2nd massive sun in the sky when the last meteor hit" is because humans haven't been around that long.

    We actually get hit by meteors a lot more often than that. We will barely miss being hit later today.

    "Or why didn't the Earth become extremely hot as the sun passed? "
    IF Nemesis came through our solar system millions of years ago, we have no way of knowing if Earth briefly became hotter since no one was around to observe this. But Nemisis can pass through the solar system without coming close to Earth. If Nemisis came close to Earth, or any planet, that planet would now have a very eccentric orbit. If Nemisis came close to the Sun, then all the planets would now have very eccentric orbits. So its safe to say that that hasn't happened. IIRC, the Nemisis proponents never envisioned it passing through the solar system's planetary region. It just dropped from 1 AU to the inner Oort Cloud, far from the planets.

    In my opinion, the WISE survey that adjacent mentions put a second nail in the coffin of the Nemisis idea. The first nail was the Hipparcos survey. Nemisis, if it exists, should have a very large parallax. Hipparcos, designed to measure parallax, spotted no such object.
  7. Sep 7, 2014 #6
    Gravity and the shape of the Earth are "only a theory".

    In this case, Nemesis is a particularly speculative and unlikely hypothesis. If there were a star orbiting our sun, we would be able to see it with the weakest telescopes and it would be of a few very specific colors, so it seems unlikely that nobody would have caught onto it (one could design a computer program to search star catalogs to find such a star of an appropriate magnitude and color and then confirm it by measuring the parallax.)

    Such searches have all turned out negative, strongly suggesting that this hypothesis has been roundly disproved.

    Periodic extinction events are an interest of mine, but Nemesis seems a rather far-fetched and disproved hypothesis.
  8. Sep 7, 2014 #7


    User Avatar
    Science Advisor

    As everyone else has said, Nemesis is an unlikely hypothesis with no evidence to back it up. But in reference to this question, who do you think was around 26 million years ago to see it? Humans have only been around for about 0.2 million years, and have had recorded history for only about .002 million years.
  9. Sep 7, 2014 #8


    User Avatar

    Staff: Mentor

    A second star would need to be very small and very dim, shining almost entirely in the far IR range. Even then, we have IR telescopes that should have detected any object with such properties nearby. The fact that we haven't detected such an object nearby is reason to believe that it doesn't exist. It's possible that we've somehow missed it, but that's an extraordinarily unlikely possibility.
  10. Sep 7, 2014 #9

    Vanadium 50

    User Avatar
    Staff Emeritus
    Science Advisor
    Education Advisor
    2017 Award

    Just to rephrase what has been said:

    If Nemesis existed, we would see it. We don't.
  11. Sep 9, 2014 #10
    The Nemesis hypothesis was reasonable when first proposed in 1984, a brown dwarf with a highly elliptical orbit and a period of about 26 million years. There seemed to be a pattern in asteroid hits, which are pretty well documented and dated. There was also a big signal-to-noise issue, so that the pattern was not at all obvious. At the time, no systematic survey of the outer solar system had yet been made. Since then, the issue has been largely resolved. The original data has been reexamined, and found to be all noise, no signal. We now have better telescopes, and not just in the visible-light range. Nemesis, if it existed, should have been found by now.

    Last edited: Sep 9, 2014
  12. Sep 9, 2014 #11
    Strictly as an aside, because the methodology for detecting a sky object is more sophisticated now, is that both Uranus and Neptune were observed many times before being discovered. Uranus can be seen with the naked eye, under good conditions. Neptune was seen in telescopes without it being known it was really a planet. Establishing Uranus and Neptune as planets meant separate direct observations of them to see that they were moving and calculate their orbits.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook