00:00 Supernovas are powerful explosions in the universe that can help us better understand the rest of the universe.

01:37 Supernovas are rare but incredibly bright explosions in our galaxy that can be seen in the sky during the day and have been recorded throughout history.

03:01 Chinese and Roman astronomers may have recorded supernovas, with Chinese astronomers potentially observing 20 different supernovas over 2,000 years, but it is difficult to determine if ancient sources actually saw supernovas or just comets; the brightest recorded supernova was in 1006 and the last supernova in our galaxy visible without telescopes occurred in 1604, with the advent of telescopes leading to the discovery of unexplained phenomena such as stars suddenly becoming brighter, and in the 20th century, astrophysicists determined that supernovas are giant explosions and that nebulas are the remnants of supernovas.

04:33 Supernovas occur when a single large star collapses, and this happens when the star exhausts its hydrogen and begins fusing heavier elements until it reaches iron, at which point fusion stops and gravity takes over.

05:59 Supernovas can result in the formation of black holes or neutron stars, depending on the size and mass of the star, and they can also occur in binary star systems where one star becomes a white dwarf and starts stealing matter from its partner star.

07:33 Supernovas, particularly type 1 supernovas, are important because they explode with the same force and mass, making them a "standard candle" that astronomers can use to calculate distances, and they are also responsible for creating heavy elements.

08:59 Supernovas are responsible for creating heavy elements, including those found in our bodies, and they provide the energy needed to fuse these elements together.