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Astronomers Find Sun's Twin
mroch writes "Space.com is reporting that astronomers may have found a solar twin -- a star almost exactly like our own Sun. Interesting tidbits from the article include: "The star, 18 Scorpii, sits about 47.5 light-years away in the constellation Scorpio, and has long-been suspected of being Sun-like. [...] The star burns slightly hotter than the Sun, at 5,789 degrees Kelvin compared to 5,777 degrees. It appears to rotate slightly faster than the Sun, taking 23 days to complete a rotation rather than the Sun's 25." It boggles my mind to think that we can measure temperature that exactly from 279,000,000,000,000 miles away, and that they are complaining over a 12-degree difference."
Distance actually does not matter with respect to the method used to measure the temperature, as long as you have enough light, and there is no disturbing medium in between. Both conditions seems to be met.
They can determine the temperature by the wavelengths of light given off by the star.
And those dozen degrees are in Kelvin. These aren't your ordinary units of measurement we're talking about.
I have been pwned because my
IIRC, the temperature is measured by the colour of the sun. That doesn't change the further away you get, so its just as accurate over long distances as short. However, there is the problem of dopler shift if the stars are moving away/toward each other.
"When I grow up, I want to be a weirdo"
nt
From The U.S. Metric Association
The kelvin (K) temperature scale is an extension of the degree Celsius scale down to absolute zero, a hypothetical temperature characterized by a complete absence of heat energy. Temperatures on this scale are called kelvins, NOT degrees kelvin, kelvin is not capitalized, and the symbol (capital K) stands alone with no degree symbol. [In 1967 the new official name and symbol for "kelvin" were set by the 13th General Conference on Weights and Measures (CGPM).]
I like David Nash's list of 50 nearby sunlike stars within 50 light years.
18 Scorpii is on there, as is the infamous Tau Ceti. 18 Scorpii was one of the four closest matches.
Binary geeks can count to 1,023 on their fingers
Actually, that distance would be more like 2.7862056^14 miles.
186,000 miles/second x 60 seconds/minute x 60 minutes/hour x 24 hours/day x 365 days/year x 47.5 years.
There are no stupid questions, only stupid people asking questions.
Astronomers look at the spectrum of the star--the relative intensities of each wavelength of light produced by the star's heat. Assuming the star is a black-body radiator (which isn't totally true, but pretty darn close), using first principles you can solve for the temperature of such and object as a function of the peak wavelength of light radiated. See "Thermal Physics" by C. Kittel and H. Kroemer for a better discussion.
Also, single wavelength filters (like your green sheet of plastic) aren't a natural byproduct of nature, and wouldn't be found between here and the aformentioned star. What would would find, however, is interstellar dust, or clouds of hydrogen, helium, lithium, and other light elements. When the light passes through these clouds, certain frequencies of light are absorbed, and certian frequencies are flouresced, but these frequencies are predictable, and the overall shape (and especially the peak) of the spectrum is not changed beyond recognition. "Introduction to Quantum Mechanics" by D. Griffiths and "Introduction to Astronomy and Astrophysics" by Zeilik and Gregory should help you out with spectra and spectral lines.
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No.
"Left" and "right" have their origins in the seating arrangements of a pre-Revolution French parliament. Nobles sat on the right, commoners (or rather, their representatives, who weren't quite so common) sat on the left. Thus, generally, being on the right was to support the privileged class; being on the left was to support the common people and more equality.
In their modern forms, the right supports (and usually hopes to join) the "privileged nobles" of the capitialist class, those to whom the state has granted control of the means of production; the left seeks a more equitable arrangement, supporting the rights and interests of the "common" laborers.
Properly, "right" and "left" refer to economic arrangements. Using them to talk about the orthogonal political dimensions of legislated morality and foreign policy results in great confusion.
Tom Swiss | the infamous tms | my blog
You cannot wash away blood with blood
This answers the question of what advances are needed. Basically, we need either laser-powered solar sails, or we need antimatter propulsion. Even then, the trip would still take a long time and be enormously expensive.
What if something in between the star and Earth is changing the wavelength of the light? I can shine a light-bulb through a green sheet of plastic, and change it
Wrong. Your filter can reduce the brightness at various wavelengths, but you CANNOT(*) change the wavelength. You can forget about brightnesses and calculate the temperature by measuring frequency behaviours.
(*) Footote: Yes, there are a handful of materials that can double or halve the wavelength of light, but there is no way in hell an enormous windowpane of some obscure mineral is sitting between us and another star - and if there were then we would blatantly see frequency doubling or halving.
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