What Are Supernovae?
The 'nova' or 'novae' part of the name means 'new' in Latin. This is because when they erupt and grow brighter, it looks like there is a new star in the sky. If we are referring to more than 1 supernova, we call them supernovae. When reading scientific papers, you may see astronomers using SN or SNe rather than writing out the whole word.
Scientists think that on average, a star in the Milky Way should explode as a supernova once every 50 years. However, one has not been seen in our own galaxy, the Milky Way, since 1604. Johannes Kepler was the one to see and record it, and he did so before the invention of the telescope.
Of course, there may have been more recent supernovae in the Milky Way that we missed.
About half of our galaxy is hidden from us by the dust, gas, and super-massive black hole, that lurk in its centre. Since the late 20th century, it has become easier to spot supernovae. This is due to infrared telescopes like Keck and the VLT, which can see through the dust and gas that blocks visible light.