Changes

A supernova is the explosion of a very large [[star]] such that the star becomes extremely bright, perhaps even one billion times brighter than our [[sun]].  

A supernova is the explosion of a very large [[star]] such that the star becomes extremely bright, perhaps even one billion times brighter than our [[sun]].  

In 1054, Chinese astronomers recorded a supernova so bright that it was visible during the day. The explosion left behind a pulsar and a huge cloud of gas and dust known as the [[Crab Nebula]], which still can be seen today. [http://www.nasa.gov/worldbook/supernova_worldbook.html]

In 1054, Chinese astronomers recorded a supernova so bright that it was visible during the day. The explosion left behind a [[pulsar]] and a huge cloud of gas and dust known as the [[Crab Nebula]], which still can be seen today. [http://www.nasa.gov/worldbook/supernova_worldbook.html]

==External links==

==External links==