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Enigmatic Planets, Supernovae, and Supercomputers: Astronomy Outside the Box

NASA, ESA, and G. Bacon (STScI)
his is an artist's impression of supernova 1993J, an exploding star in the galaxy M81 whose light reached us 21 years ago.

How many planets are there in our solar system? It used to be such an easy question. Nine - Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto. Then Pluto got demoted to a dwarf planet, so eight. But scientists now say they've found evidence of a ninth planet- likely an icy, gaseous planet about 10 times the mass of Earth - far beyond Neptune.

The postulated size of Planet Nine is significant because it falls into a category known as a Super-Earth - several times larger than Earth (the largest of the terrestrial planets of the inner solar system), but significantly smaller than the giant ice and gas planets of the outer solar system. Such Super-Earths are common in other parts of the universe, but this would be the first in our solar systemand scientists have long wondered why they are missing. 

Of course, no one has actually seen Planet Nine. Rather, its existence has been inferred from unusual behavior by six other objects in the outer solar system. And confirming Planet Nine's existence could take a while. It likely takes about 20,000 years to complete its orbit around the sun, and nobody knows exactly where it is. On top of that, it's so far away, that - if it exists - it will be extremely faint. In other words, we can't just point a telescope at it and snap a photo.

If a long undetected ninth planet seems far-fetched, consider this: in the 1980's, some astronomers speculated that the sun might have had a companion star. Most stars are in binary systems, making our solo sun rather unusual. But, the companion star theory has been laid to rest and, along with it goes the possibility that our sun - billions of years from now - could end as a cosmic fireball known as a supernova.

Off-the-wall conjectures and uncertainty are nothing new to astronomers. The field has a long history of theorizing everything from particles to planets in order to explain observed phenomena, and then going in search of evidence to support the theory. The Higgs Boson is a prime example - first theorized in the 1970's, but not confirmed until 2012.

It's not your traditional scientific experiment, but then, it's not like we have multiple universes at our disposal. Even if we did, we wouldn't be able to manipulate them in the ways scientists might like. At least, not in the real world.

But supercomputing could provide the next best thing. Astrophysicists have made computer models of the universe (or at least aspects of it). In some cases, the physics is actually simpler than the equations that go into global climate models. Those models have yielded some surprises, and those unexpected results can nudge scientists to think differently about their subject matter.

The field of astronomy traces its roots back two millenia, but there's no shortage of big questions left to answer. In fact, modern astrophysics seems to be addressing ever more fundamental aspects of the universe - dark matter and energy, the rate at which our universe is expanding, and the possibility that there could be an infinite number of other universes. Some serious thinking outside the box is in order.

Guests:

  • Regina Jorgenson - Director of Astronomy, Maria Mitchell Association
  • Robert Fisher - Associate Professor in the Physics Department, U. Mass. Dartmouth

Robert Fisher will give a TED-style ARNIE (Art. Research. Nexus. Innovation. Education) Talk at U Mass Dartmouth on Wednesday, February 3, 2016.

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