Donald.McLean
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Why is the Hubble Telescope in space?
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30 votes

As @astromax observed, one of the primary factors that makes a space based telescope better than an equivalent telescope of the same size is scattering. Along with scattering, there is also ...

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Why Do Planets Revolve Faster When they Are Closer to Their Parent Star?
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10 votes

Velocity is a form of kinetic energy, while height within a gravity well is a form of potential energy. For an orbiting body, conservation of energy will keep the total energy constant. So as a ...

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Is "Main Sequence" a temporal sequence?
8 votes

The main sequence is mostly a plateau that a star reaches after it is fully formed but before it begins to run low on hydrogen to fuel normal fusion reactions. And yes, the sequence is mostly an ...

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Why is the Earth's center still hot after millions of years?
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7 votes

There is a nice article from Scientific American, but the main point is: There are three main sources of heat in the deep earth: (1) heat from when the planet formed and accreted, which has not yet ...

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Earth and ferromagnetism
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7 votes

Actually, the core has two parts. The outer core is liquid, while the inner core is solid. As explained in the Wikipedia article about Earth's magnetic field: The Earth's magnetic field is mostly ...

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Why are Hubble images "Cut"
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6 votes

The "stair-step" pattern visible in the first image is characteristic of the the Hubble's Wide Field and Planetary Camera 2 (WFPC2). This pattern is created by the arrangement of the four CCD chips. ...

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How can I measure the mass of eclipsing binary stars?
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5 votes

It depends. For many categories of stars, it is possible to determine the approximate mass of the star from its non-redshifted spectrum. Stars on the main sequence: this table of spectral ...

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Is Earth's 1g solid surface gravity unusually high for exoplanets?
4 votes

Surface gravity is a function of two things: Mass Radius Mass is proportional to the cube of the radius times the mean density. Gravity is proportional to the square of the radius. As a result, is ...

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What is the oldest known prediction of constellation positions?
3 votes

No, there is no possible way that humans from any known civilization in the first century AD would have been able to extrapolate current constellation positions. Prior to the work of Johannes Kepler ...

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Brightest star of the night sky
2 votes

The best way to find a particular star/planet/etc. is almost certainly to use a star map of some sort. For example, doing a Google Image search for "star map sirius" would get you quite a few ...

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What must/do astronomers reveal beyond their academic papers?
0 votes

All data from the Hubble Space Telescope that is used in scientific research is released into the public domain (usually within one year, sometimes less) and available from the Mikulski Archive for ...

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