The first-ever discovery of an extraterrestrial radioactive isotope on Earth has scientists rethinking the origins of the elements on our planet. The tiny traces of plutonium-244 (Pu-244) were found in ocean crust alongside radioactive iron-60. The two isotopes are evidence of violent cosmic events in the vicinity of Earth millions of years ago.
“I like studying these kinds of stars because I am fascinated by their instability. They are doing something weird,” said Kerstin Weis, a luminous blue variable expert at Ruhr University in Bochum, Germany. The Hubble Space Telescope recently captured the nebulosity surrounding the rare luminous blue variable star AG Carinae pictured above. Less than 50 luminous blue variables are known to exist among our local group of neighboring galaxies.
So far, we have had only close calls from gamma ray explosions so large, scientists have suggested, that if they occurred within our solar neighborhood (less than 1,000 light years) they could potentially trigger mass extinctions on Earth.
“Somewhere,” said Carl Sagan, “something incredible is waiting to be known” –“I’ve never seen anything like this before in the local universe,” said Stephen Smartt, an astrophysicist at Queen’s University Belfast and a lead scientist for the Hawaii-based ATLAS survey, about “something incredible” –a mysterious cataclysm in a neighboring galaxy that rocked the world’s astronomy community with its discovery on June 16, 2018.
Seething supergiant Betelgeuse –a star so huge it could someday collapse into a black hole or neutron star, which would make it the closest black hole to Earth some 725 light-years distant– has displayed unprecedentedly large drop in its brightness in early 2020, prompting speculation that the pulsing may be a dire prelude. A new study by an international team of scientists concluded that the star is in the early core helium-burning phase (more than 100,000 years before a supernova event) and has smaller mass and radius–and is closer to Earth–than previously thought. If the bright-red object replaced the Sun at the center of our solar system, its outer surface would extend past the orbit of Jupiter.
When we consider the origins of life in our Solar System, a remarkable discovery has to be taken into account –the Solar System is substantially over-abundant in metals compared with average interstellar abundances at the time of its formation 4.6 billion years ago. These solar abundances are similar to present interstellar abundances, an anomaly that remains a mystery. One possibility scientists suggest is that the Sun formed much closer to the galactic center than its current position, which may have resulted in a plentiful supply of raw materials in the solar nebula from which to form the Earth and its biosphere.