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What is a Comet? – Astronomy – Space

By |2019-04-18T05:32:51-07:00August 17th, 2017|Physics|

A comet in the night sky What are comets made of? Comets are balls of leftover rock and ice in space. They started out when a star exploded into a supernova. What is a supernova? More about ice All our space articles When were the first comets? A nebula formed, and then most of the material in our nebula merged together, about [...]

What is jade? Metamorphic rock

By |2018-04-21T12:09:20-07:00June 26th, 2017|History|

What is jade? Jade rock from Alaska Jadeite and nephrite Jade is really two kinds of metamorphic rock, jadeite and nephrite, that look pretty much exactly the same. Scientists can tell them apart using chemical tests and x-rays. Like quartz, both jadeite and nephrite are chains of silicon and oxygen atoms. Why is [...]