At just 140 years old, this recently discovered supernova remnant is the youngest yet found. Obscured by dust until X-ray and radio telescopes revealed it, "G1.9+0.3" came into being shortly after the United States' Civil War.

Supernova remnants are caused when the debris thrown outwards by the explosion crashes into surrounding material, generating a shell of hot gas and high-energy particles that glows brightly in X-rays, radio waves and other wavelengths for thousands of years. In the case of G1.9+0.3 the material is expanding outwards at almost 35 million miles per hour, or about 5% the speed of light, an unprecedented expansion speed for a supernova remnant. Another superlative for G1.9+0.3 is that it has generated the most energetic electrons ever seen in a supernova remnant.

Link to Chandra X-Ray Observatory article