If you take normal matter — something made of protons, neutrons and electrons — and compress it as far as it will go, something incredible happens. At high enough temperatures and densities, something requiring a tremendous amount of mass hundreds of thousands of times as great as planet Earth, nuclear fusion occurs, giving rise to a living star. Burn through all the hydrogen, though, and your star’s core will be made of helium, which will collapse further and heat up to even higher temperatures and densities. Reach a critical temperature and helium will be begin burning, forming carbon. After some time, you’ll run out of helium, too, where your now-carbon core begins to contract, heating up and becoming more dense. At this stage, one of two critical things can occur.
Either your star isn’t massive enough to ignite carbon, in which case it will gently blow off its outer layers and form a white dwarf at the center: a degenerate mass of atoms that’s maybe the mass of the Sun but only the physical size of Earth. This sounds like an incredible state of matter, but it’s still relatively sparse, at “only” a few hundred thousand times the density of our planet. The atoms themselves are sufficient to prevent gravitational collapse from taking things further.
Imagine making plans with your friends — by walking to their house to talk in person.
That’s the norm at Green Bank, West Virginia, where its 143 residents can’t rely on their cellphones or tablets to connect with friends and loved ones because all wireless devices are forbidden.
Located within a 13,000-square mile area known as the National Radio Quiet Zone, Green Bank houses the National Radio Astronomy Observatory, which operates the world’s largest radio telescope.
“It’s the study of the natural radio emissions that are coming from bodies in space,” explained Michael Holstine, the observatory’s business manager.
Standing 485-feet tall and weighing nearly 17-million pounds, the telescope is so large that a college football stadium could fit inside the dish. It’s also incredibly sensitive to electronic interference and, Holstine said, so powerful that it could pick up “the energy given off by a single snowflake hitting the ground.”
An enormous celestial gas cloud that first left the Milky Way when dinosaurs roamed the Earth is speeding back towards the galaxy at roughly 700,000 miles per hour, a study in The Astrophysical Journal Letter Reports.
The cloud – known as “The Smith Cloud” – was first ejected from the Galaxy some 70 million years ago. It is full of sulfur, over 11,000 light years long, nearly 2,500 light years wide, and has the mass of roughly one million suns. It is shaped like a comet and contains no stars, making it invisible in optical wavelengths.
Though hundreds of enormous high-velocity gas clouds whiz around the outskirts of our galaxy, this so-called “Smith Cloud” is unique because its trajectory is well known.
Hubble Space Telescope astronomers are finding that the old adage, “What goes up, must come down” even applies to an immense cloud of hydrogen gas outside our Milky Way Galaxy. The invisible cloud is plummeting toward our galaxy at nearly 700,000 miles (1,100,000 kilometers) per hour.
Though hundreds of enormous high-velocity gas clouds whiz around the outskirts of our galaxy, this so-called “Smith Cloud” is unique because its trajectory is well known. New Hubble observations suggest it was launched from the outer regions of the galactic disk around 70 million years ago. The cloud was discovered in the early 1960s by Gail Smith, who detected the radio waves emitted by its hydrogen.
The cloud is on a return collision course and is expected to plow into the Milky Way’s disk in about 30 million years. When it does, astronomers believe it will ignite a spectacular burst of star formation, perhaps providing enough gas to make 2 million Suns.
Since astronomers discovered the Smith Cloud, a giant gas cloud plummeting toward the Milky Way, they have been unable to determine its composition, which would hold clues as to its origin. Astronomers have now determined that the cloud contains elements similar to our sun, which means the cloud originated in the Milky Way’s outer edges and not in intergalactic space as some have speculated.
The astronomers found that the colossal cloud loud is as rich in sulfur as the Milky Way’s outer disk, a region about 40,000 light-years from the galaxy’s center and about 15,000 light-years farther out than our sun and solar system are. This means that it was polluted by material from stars. This would not happen if it were pristine hydrogen from outside the galaxy. Instead, the cloud appears to have had an intimate relationship with the Milky Way, but was somehow ejected from the outer Milky Way disk about 70 million years ago and is now boomeranging back onto its disk.