Planet, or star?


It used to be simple. Star were the objects that shined. Planets go around stars. But the hunt for ever-colder star-like bodies two years ago led to a a new class of such objects. However, until now no one has known exactly how cool their surfaces really are – some evidence suggested they could be room temperature.

A new study shows that while these brown dwarfs, sometimes called failed stars, are indeed the coldest known free-floating celestial bodies, they are warmer than previously thought with temperatures about 250-350 degrees Fahrenheit. To reach such low surface temperatures after cooling for billions of years means that these objects can only have about 5 to 20 times the mass of Jupiter. Unlike the Sun, these objects’ only source of energy is from their gravitational contraction, which depends directly on their mass.

“If one of these objects was found orbiting a star, there is a good chance that it would be called a planet,” says Trent Dupuy, a Hubble Fellow at the Harvard-Smithsonian Center for Astrophysics. But because they probably formed on their own and not in a proto-planetary disk, astronomers still call these objects brown dwarfs even if they are “planetary mass.”

The new data also present new puzzles to astronomers that study cool, planet-like atmospheres.
Planets, stars, orin between? Additional objects discovered in the past two years remain to be studied and will hopefully shed light on some of these outstanding issues.

Planets, planets, everywhere


Every year we see to find more and more astonishing discoveries about planet survivability. First we found that binary stars can have planets, then we found that huge, short lived stars can have planets. No we find that old stars can have planets.

A star, called TW Hydrae, thought to be too old for plan­et mak­ing has been found mak­ing new plan­ets. The old star is about 176 light years from Earth and NASA reports that astronomers using the Her­schel Space Tele­scope found that the star may be big enough to make fifty more Jupiter-sized plan­ets as the artist’s illus­tra­tion shows above.

Adwin Bergin, an astronomer at the Uni­ver­si­ty of Michi­gan in Ann Arbor and leader of the study, said in the announce­ment, “We didn’t expect to see so much gas around this star. Typ­i­cal­ly stars of this age have cleared out their sur­round­ing mate­r­i­al, but this star still has enough mass to make the equiv­a­lent of 50 Jupiters.”

And with every extra planet, comes more and more chance for the existence of life.

Pluto full house


Pluto appears to have its own mini solar system. There are now five confirmed moons for this rocky outcrop. Once the last known planet, it is now deleted from the planet club. Unfortunately for Pluto, the ability to host moons does not help its case for re-entry into this the current gang of eight. In fact it does the opposite in some ways. Pluto was always a bit of a strange one. It was too small, too far away and its main moon was too big. New it seems to have a surplus of smaller moons. This may shake up our current theories of how these outer solar system objects are formed, but it’ll not get Pluto back into the planet club.

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Newtons’s law reign supreme once again

Kepler planets published in science


Back way back when, our solar system ended at saturn, then after some debate Uranus was added. We had saw Uranus before loads of times, but it moved so slow in the sky that no one suspected it was a planet. Then we had a problem. Uranus was not moving it way it should be according to Newtons’s laws of gravity. As the entire industrial revolution had been built on the concepts of Newton’s law, this was a problem. Rather than throw away Newton’s law, two groups of astronomers set about the idea that there might be another big planet in our solar system, beyond the orbit of Uranus and tugging on Uranus. Both groups came to the same conclusion, predicting the existence of Neptune. They predicted the exact location to look for Neptune, and there is was. A triumph for science,for cause and effect and for the laws of gravity.

Fast forward a few hundred years and history has repeated itself. The time a planet around another star has an orbit which disagrees with newton’s law. Once again, the correction is accounted for by assuming more planets.

Science repeats itself, and Newton reigns supreme once more.


My students hate it when I tell them Pluto is not a planet. After all, many are from las cruces and even went to the Tombaugh school. But the one thing they hate even more than being told it, is when they work through the logic themselves and then decide it is not a planet. It raise tow interesting debates though.

The first stage of all science seems to be noticing and grouping. Then, after years of making new discoveries we always go back to the the grouping. Somehow we feel the need to reclassify

Second, who should make these decisions on reclassifying. The scientists or the public?