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Thread: Astronomy

  1. #436
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    10 times more massive than the Earth. It is amazing what we might have missed. I wonder if it's discovery would eliminate the need for dark matter in our solar system?

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    Today space.com has an item on the next space telescope, WFIRST, due operational 2014. It may be this will do what you are looking for?

  4. #439
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    Quote Originally Posted by YesNo View Post
    10 times more massive than the Earth. It is amazing what we might have missed. I wonder if it's discovery would eliminate the need for dark matter in our solar system?
    No, even a planet 10X larger than Earth would be a midget against Jupiter and its gravitational impact would be negligible, which is why it's been hiding for so long.

    The planets we do know about are putting on a stunning display at the moment, with Saturn, Jupiter, Mars & Venus in line with the rising sun. We've been waiting for a clear morning and were up at 4 to have a look.

    Saturn in particular was sensational, with the moons gleaming like they'd been polished.

    Best of all was as we were showing the 6 year old the Southern Cross, a meteor flitted past.
    Go to work, get married, have some kids, pay your taxes, pay your bills, watch your tv, follow fashion, act normal, obey the law and repeat after me: "I am free."

    Anon

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    Yes, the mornings can be very nice. I was up early this morning but it was overcast.

  6. #441
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    Atheist, You have an interest in astronomy, I see. Can you actually see the moons of saturn? What kind of telescope do you have?

  7. #442
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    The SOCIETY for POPULAR ASTRONOMY

    Electronic News Bulletin No. 414 2016 January 24

    Here is the latest round-up of news from the Society for Popular Astronomy. The SPA is arguably Britain's liveliest astronomical society, with members all over the world. We accept subscription payments online at our secure site and can take credit and debit cards. You can join or renew via a secure server or just see how much we have to offer by visiting http://www.popastro.com/

    EVIDENCE OF A REAL NINTH PLANET

    California Institute of Technology

    Caltech researchers have found evidence of a giant planet tracing a bizarre, highly elongated orbit in the outer Solar System. The object, which the researchers have nicknamed Planet Nine, is supposed to have a mass about 10 times that of the Earth and orbits about 20 times further from the Sun on average than Neptune (which does so at an average distance of 2800 million miles). In fact, it would take the (still-hypothetical) planet between 10,000 and 20,000 years to orbit round the Sun. The researchers' evidence for the planet's existence came through mathematical modelling and computer simulations; they have not observed the object directly. There have been only two true planets discovered since ancient times, and this would be a third. The putative ninth planet -- at 5,000 times the mass of Pluto -- is sufficiently large that there should be no debate about whether it is a true planet. Unlike the class of smaller objects now known as dwarf planets, Planet Nine gravitationally dominates its neighbourhood of the Solar System. In fact, it dominates a region larger than any of the known planets.

    The road to the theoretical discovery was not straightforward. In 2014, astronomers noted that 13 of the most distant objects in the Kuiper Belt are similar with respect to an obscure orbital feature. To explain that similarity, they suggested the possible presence of a small planet. A year-and-a-half-long collaboration began to investigate the distant objects. Fairly quickly it was realized that the six most distant objects from the original 13 under study all follow elliptical orbits that point in the same direction in space. That is particularly surprising because the outermost points of their orbits move around the Solar System, and they travel at different rates. It is almost like having six hands on a clock all moving at different rates, and when you happen to look up, they're all in exactly the same place. The odds of having that happen are something like 1 in 100. But on top of that, the orbits of the six objects arealso all tilted in the same way -- pointing about 30 degrees downward in the same direction relative to the plane of the eight known planets. The probability of that happening is about 0.007%. It could not happen randomly, so something must be shaping the orbits.

    The first possibility investigated by astronomers was that perhaps there are enough distant Kuiper-Belt objects -- some of which have not yet been discovered -- to exert the gravity needed to keep that sub-population clustered together. The researchers quickly ruled that out when it turned out that such a possibility would require the Kuiper Belt to have about 100 times the mass that it actually has. That left them with the idea of a planet. Their first instinct was to run simulations involving a planet in a distant orbit that encircled the orbits of the six Kuiper-Belt objects, acting like a giant lassoo to wrangle them into their alignment. That almost works but does not provide the observed eccentricities precisely. Then, effectively by accident, the team noticed that if they ran their simulations with a massive planet in an anti-aligned orbit -- an orbit in which the planet's closest approach to the Sun, or perihelion, is 180 degrees away from the perihelion of all the other objects and known planets -- the distant Kuiper-Belt objects in the simulation assumed the alignment that is actually observed. Through a mechanism known as mean-motion resonance, the anti-aligned orbit of the ninth planet actually prevents the Kuiper-Belt objects from colliding with it and keeps them aligned. As orbiting objects approach each other they exchange energy. So, for example, for every four orbits Planet Nine makes, a distant Kuiper-Belt object might complete nine orbits. They never collide. Instead, like a parent maintaining the arc of a child's swing by periodic pushes, Planet Nine nudges the orbits of distant Kuiper-Belt objects such that their configuration with relation to the planet is preserved.

    Planet Nine's existence helps to explain more than just the alignment of the distant Kuiper-Belt objects. It also provides an explanation for the curious orbits that two of them trace. The first of those objects, dubbed Sedna, was discovered in 2003. Unlike standard-variety Kuiper-Belt objects, which can get gravitationally 'kicked out' by Neptune but can then return back to it, Sedna never gets very close to Neptune. A second object like Sedna, known as 2012 VP113, was announced in 2014. The presence of Planet Nine in its proposed orbit naturally produces Sedna-like objects by taking a standard Kuiper-Belt object and slowly pulling it away into an orbit less connected to Neptune. But the real clincher for the researchers was the fact that their simulations also predicted that there would be objects in the Kuiper Belt on orbits inclined perpendicularly to the plane of the planets. In the last three years, observers have identified four objects tracing orbits roughly along one perpendicular line from Neptune and one object along another. Where did Planet Nine come from and how did it end up in the outer Solar System? Scientists have long believed that the early Solar System began with four planetary cores that went on to grab all of the gas around them, forming the four gas planets -- Jupiter, Saturn, Uranus, and Neptune. Over time, collisions and ejections shaped them and moved them out to their present locations. But there is no reason why there could not have been five cores, rather than four. Planet Nine could represent that fifth core, and if it got too close to Jupiter or Saturn, it could have been ejected into its distant, eccentric orbit. Researchers continue to refine their simulations and learn more about the planet's orbit and its influence on the distant Solar System. Meanwhile, astronomers have begun searching the skies for it. Only a rough orbit is indicated, not the precise location of the planet. If the planet happens to be close to its perihelion, astronomers should be able to find it in images captured by previous surveys. If it is in the most distant part of its orbit, the world's largest telescopes will be needed to see it. If, however, Planet Nine is now located anywhere in between, many telescopes might have a shot at finding it.

  8. #443
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    I wonder if it would become visible without a telescope at some point in the future?

    I'm surprised that many smaller planets would not have the same gravitational effect as one large one.

  9. #444
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    We do know that Jupiter acts as a magnet for all sorts of stray asteroids, like the one that broke up into smaller bits and that crashed into Jupiter.

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    This is an interesting explanation of the birth of our moon.

    http://www.space.com/31763-moon-crea...ekly_2016-1-29

    Very violent, and creating a moon that is unusually-large in terms of the relationship between the earth and the moon, such that tides play an important part in creating earth's seas, and producing a very lively interaction.
    Last edited by Dreamwoven; 01-31-2016 at 05:51 AM. Reason: prove some background

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    http://earthsky.org/space/is-our-mil...laxy-a-zombie?

    A "dead" galaxy, that has stopped producing more stars? An interesting thought...

  12. #447
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    Using the zombie metaphor seems odd. The galaxy is just not as active in producing new stars as others are. But those newer, blue stars don't live as long as the red ones. So maybe being a zombie means a longer life.

    It was interesting that they needed help from volunteers to manually classify galaxies at the galaxyzoo site.

  13. #448
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    galaxy zoo is a new idea to me, not come across it before. I've added it to my astronomy tags. The website talks about the zooniverse...

    Thanks, YesNo.

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    I haven't actually gone to the site since I figured I wouldn't have time to volunteer for any of the activities they might have at the moment, but it is interesting that there is something any of us could do to help these guys. We could become more than consumers of this information.

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    Pluto has strange floating hills. Read about them here

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