North Star May Be Wasting Away 129
sciencehabit writes "The North Star, a celestial beacon to navigators for centuries, may be slowly shrinking, according to a new analysis of more than 160 years of observations. The data suggest that the familiar fixture in the northern sky is shedding an Earth's mass worth of gas each year."
Re:Oh my god! (Score:3, Informative)
We do however have wonderful things called "Com-pass-es" that work similarly (even inside and in daytime).
-GiH
Re:Oh my god! (Score:5, Informative)
The Earth precesses once ever 26000 years. In 13000 years north will be pointed towards Vega.
Cough. Earth's Mass?!? (Score:2, Informative)
That's not exactly a lot. I'm sure our own dear Sun is losing that much mass every year and you still see 5 Billion on its birthday card.
Slow astrophysical news day, I guess.
Re:Cough. Earth's Mass?!? (Score:5, Informative)
Mass of the sun is 330,000 times the mass of earth.
So if it were losing an Earth-Mass yearly it would have had to be 7 times as massive as today at the beginning of the Pleistocene, and would only have a life expectancy of about 330,001 years left.
The Sun appears to have been active for 4.6 billion years and has enough fuel to go on for another Five billion years or so. [solarviews.com].
So I think you may have lost a few digits (in the exponents) when making your calculations.
Re:Cough. Earth's Mass?!? (Score:4, Informative)
Polaris is listed, at least in Wikipedia, at 7.54 solar masses. Also, it is a ternary system: one large star, a smaller star and a white dwarf.
Re:Oh my god! (Score:5, Informative)
You're right
Karma whoring:
"...Gamma Cephei (also known as Alrai, situated 45 light-years away) will become closer to the northern celestial pole than Polaris around AD 3000. Iota Cephei will become the pole star some time around AD 5200.
First-magnitude Deneb will be within 5 of the North Pole in AD 10000.
The brilliant Vega in the constellation Lyra is often touted as the best North Star (it fulfilled that role around 12000 BC and will do so again around the year AD 14000). However, it never comes closer than 5 to the pole.
When Polaris becomes the North Star again around 27800 AD, due to its proper motion it then will be farther away from the pole than it is now, while in 23600 BC it came closer to the pole.
In 3000 BC the faint star Thuban in the constellation Draco was the North Star. At magnitude 3.67 (fourth magnitude) it is only one-fifth as bright as Polaris, and today it is invisible in light-polluted urban skies..."
-Wikipedia
Re:What does it mean for Christians? (Score:4, Informative)
Hrmm I'm Catholic and have a degree in theology. And this is the first time I've ever heard that the star of Bethlehem is supposed to be Polaris - it's certainly not part of the general 'mythos' as you put it
General teaching is that the Star of Bethlehem only hung around until not long after the Wise men left. And from a more scientific viewpoint if it's true then it was likely a supernova
Relativity Speaking (Score:5, Informative)
A solar mass is over 300,000 Earths, and Polaris is atleast 7 solar masses, adjusting for the most conservative of all estimates. It's apparent magnitude is about 1.9, while the magnitude of drop off (nolonger visible to the human eye) is defined at 7 (with 6 being relatively hard except under good conditions).
Setting aside the nuclear chemistry that will occur in the meantime (which tends to increase brightness), that Polaris is, in fact, multiple stars and the overall reduction of radiative and mass pressure that will be reducing the production/consumption rate*, I would posit even losing half of its mass, it would likely still be visible in 2000 years, which means the Northern Star will have since switched to Gamma Cephei.
So, no big loss here. Personally, I, for one, welcome our new Alrainian OverStar.
****
*You know what, I'm actually going to do these in the coming weeks. This is sound like a fun problem, even though I do a lot more in theoretical particle physics than cosmology.