[johnlear]

Originally Posted by eagle

Aristarchus? Yes, but beats me what color that is!

Its a light blue.

I am sure there is an element that may glow blue under certain conditions.

Unlikely:

Out of the first 92 elements, 1 being hydrogen (H) and 92 being uranium (U), there are 90 that are naturally occuring. Technetium (Tc) and promethium (Pm) are man-made elements and do not have any isotopes occuring naturally.

One of the most common compounds of elements are the oxides, which is the compound that is produced when an element "rusts" in the presence of oxygen. Some are very reactive with air or water and do not last long in their elemental state, even if produced. Other elements, due to the arrangement of the outer shell of electrons, are very reactive with other elements and are never found out of a compound. Out of these 90 elements, 9 are gases and are usually found in their elemental states. Since many of them are inert gases, they are hard to find and even harder to pick up. There are 4 liquids: bromine (Br), cesium (Cs), gallium (Ga), and mercury (Hg).

http://www.hps.org/publicinformation/ate/q933.html

None of these have a blue glow. What does have a blue glow is the Cerenkov effect:

Čerenkov radiation (also spelled Cerenkov or Cherenkov) is electromagnetic radiation emitted when a charged particle (such as a electron) passes through an insulator at a speed greater than the speed of light in that medium. The characteristic "blue glow" of nuclear reactors is due to Čerenkov radiation. It is named after Russian scientist Pavel Alekseyevich Čerenkov, the 1958 Nobel Prize winner who was the first to characterise it rigorously.

Unlike fluorescence or emission spectra that have characteristic spectral peaks, Čerenkov radiation is continuous. Around the visible spectrum, the relative intensity of one frequency is approximately proportional to the frequency. That is, higher frequencies (shorter wavelengths) are more intense in Čerenkov radiation. This is why visible Čerenkov radiation is observed to be brilliant blue. In fact, most Čerenkov radiation is in the ultraviolet spectrum - it is only with sufficiently accelerated charges that it even becomes visible; the sensitivity of the human eye peaks at green, and is very low in the violet portion of the spectrum.

http://en.wikipedia.org/wiki/Cherenk...on#cite_note-0

Your suggestion that it is a uranium asteroid is not supported by the facts:

Uranium has the highest atomic weight of the naturally occurring elements. Uranium is approximately 70% more dense than lead, but not as dense as gold or tungsten. It is weakly radioactive. It occurs naturally in low concentrations (a few parts per million) in soil, rock and water, and is commercially extracted from uranium-bearing minerals such as uraninite (see uranium mining).http://en.wikipedia.org/wiki/Uranium

Uranium does not glow blue:

The normal color of uranium glass ranges from yellow to green depending on the oxidation state and concentration of the metal ions.

http://en.wikipedia.org/wiki/Uranium

Now there a number of elements that occur in other solar systems that do not occur on earth.This is because the 2 main factors which determine the residual matter that remains after the creation of that solar system is the amount of electromagnetic energy and the amount of mass present at the time of the creation of that solar system.

However, it is unlikely that an element created in a solar system not similar to earth, flew to our solar system, landed on our moon, assembled itself into a dome topped hexagonal shape 26 miles in diameter and then started glowing blue.