Astronomy Guide Archives - Page 10 of 10 -
Stars are massive shining spheres of hot gas, the closest of which is our Sun. Stars are primarily made of hydrogen, smaller amounts of helium, and trace amounts of other elements. Even the most abundant of the other elements present in stars are only present in very small quantities.
Astronomers are edging closer to discovering how the universe’s most supermassive black holes form — by studying the smallest galaxies.
Discovered on March 31, 2005 by Michael Brown and his team at the Palomar Observatory, the dwarf planet, Makemake, is the third largest dwarf planet in the solar system (perhaps the largest Kuiper belt object -wikipedia), with a diameter that is about 2/3 the size of Pluto.
Astronomers determine a supernova’s type in part by its spectrum and in part by its light curve, a graph of brightness changes. The energy driving a supernova’s rapidly expanding gas comes mainly from three means: the radioactive decay of freshly synthesized elements, typically nickel-56; the shock wave heating the star’s extended hydrogen atmosphere, if present; and the interaction between the supernova’s ejecta and any hydrogen gas in the vicinity.
Astronomers estimate that every second, somewhere in the observable universe, a star undergoes a supernova explosion. These stars are the source of chemical elements heavier than boron — like the calcium in our bones, the iron in our blood, and the sodium and potassium that orchestrate nerve impulses.
In the late 18th century, two scientists (John Michell and Pierre Simon Laplace) separately theorized that a star could be so massive that not even light could escape its surface. But nothing more was made of these “dark stars” until the 20th century, when Albert Einstein published his general theory of relativity.
In January 2005, Mike Brown announced the discovery of another object from the Kuiper belt, even larger than Pluto. This dwarf planet (plutoid) provisionally named 2003 UB313 or Xena, was recently officially called, Eris.
We go about our lives unaware that in the depths of space lurk invisible monsters, destroyers, powerful enough to tear apart our sun and leave our Earth a shattered burned-out ruin. We talk about one object out there whose pull is so powerful you can never escape (from it) no matter how fast you go, not even if you travel at the speed of light. We talk about black holes.
Ceres was classified as a dwarf planet, but it’s also considered an asteroid. Discovered on January 1, 1801 by Giuseppe Piazzi, Ceres has a diameter of 950 km and it is by far the largest and most massive asteroid from the asteroid belt, containing one third of the total mass of the asteroid belt.