ExpertAverage RatingsExpertise

Paul Wagner

Astronomy and telescope making. Have made at least seven telescopes, both refractors and reflectors, and have spent 30 years looking at the nighttime sky.

Harry Hayfield

Particular expert in eclipses (both solar and lunar), but able to answer most questions about astronomy or refer to a website that can help

James Gort

Questions on observational astronomy, optics, and astrophysics. Specializing in the evolution of stars, variable stars, supernovae, neuton stars/pulsars, black holes, quasars, and cosmology.

Courtney Seligman

On Vacation
returns 06/15/2016
I can answer almost any question about astronomy and related sciences, such as physics and geology. I will not answer questions about astrology and similar pseudo-scientific rubbish.

Philip Stahl

On Vacation
returns 05/30/2016
I have more than forty years of experience in Astronomy, specifically solar and space physics. My specialties include the physics of solar flares, sunspots, including their effects on Earth and statistics pertaining to sunspot morphology and flare geo-effectiveness.

Recent Answers

2016-05-24 Black Holes:

Hi Corissa    In fact, light CAN enter a black hole.  A black hole is a massive object, and light and matter both can enter it.  But it is so massive that its gravitational field is so strong that neither

2016-05-24 Stars:

Hi Corissa,    The answer is gravity. The same thing that keeps the earth together also keeps the stars together. But stars are gas, aren't they? Yes, but even the gas molecules are attracted to other

2016-05-19 universe expansion:

Hi Richard,    I'm not sure if that's actually been proposed in any peer-reviewed publication, but I don't see why that can't be viewed as one possible "explanation". Of course, we'd have to come up with

2016-05-14 Follow Up Question:

Hi Maria,    Humans have imagined all sorts of constellations before, but all were made up of the same stars we see today. In 1922, we adopted an "official" list of 88 constellations.    Please see https://en

2016-05-12 Stars:

Hi Maria,    No, astronomers are not very concerned with the way constellations will appear in the future, although they are very concerned with the positions of stars (and their positions do make up the

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