Image: David Kingham
The Perseids are a prolific meteor shower associated with the comet Swift-Tuttle. The Perseids are so-called because the point from which they appear to come, called the radiant, lies in the constellation Perseus. The name derives in part from the word Perseides (Περσείδες), a term found in Greek mythology referring to the sons of Perseus.
The stream of debris is called the Perseid cloud and stretches along the orbit of the comet Swift-Tuttle. The cloud consists of particles ejected by the comet as it travels on its 130-year orbit. Most of the dust in the cloud today is around a thousand years old. However, there is also a relatively young filament of dust in the stream that was pulled off the comet in 1862. The rate of meteors originating from this filament is much higher than for the older part of the stream. —[**]
The Greatest Mysteries of the Planets
Mercury is notoriously difficult to study, thanks to its proximity to the scorching hot and blindingly bright sun. Thus, mysteries abound. For example, Mercury has a giant core — perhaps because its outer, lighter layers got brushed off by planetary collisions long ago, but scientists aren’t sure. It also has a magnetic field and an atmosphere, both of unknown origin. In fact, the little planet leaks a steady stream of atmospheric particles, suggesting its atmosphere is somehow constantly regenerated.
Planetary scientists are still working out the details of how a once-earthlike Venus gradually morphed into the hellishly hot planet shrouded in a thick blanket of toxic gases we see today. But a bigger mystery regarding Earth’s “evil twin” is why the planet’s atmosphere swirls around it 60 times faster than the sphere spins itself; and speaking of Venus’ spin, no one knows why it goes counter-clockwise unlike all the other inner planets, such that the sun rises in the west and sets in the east.
You might think we’d have nailed down the major bullet points about our home planet’s structure and formation, but in fact, big zingers remain. We don’t know, for example, how all this water got here, and we’re uncertain about the nature of Earth’s core, which, strangely, transmits seismic waves faster in one direction than the other. Our beloved satellite has big bogglers, too. While most scientists think the moon formed from a chunk of Earth that got knocked off during an ancient impact, the theory has a hole: the theoretical impactor, dubbed Theia, should have left a residue with distinctive characteristics, but it has not been detected.
The Red Planet, now frigid, barren and seemingly deserted, spent its first 500 million or billion years as warm, wet and geologically dynamic. Scientists don’t know why it changed so drastically for the worse. They also wonder whether a more vibrant Mars once harbored life, and if it did, whether any bacteria-like Martian organisms managed to adapt to the harsher environs that took over, and are still eking out an existence there.
Like a carefully dyed Easter egg, Jupiter is girded by lighter-hued bands called zones and darker bands called belts. But are these stripes merely surface features overlaying a uniform inner ball of gas, or are the zones and belts actually the tops of concentric cylinders that make up the planet? Whole stripes have been known to disappear without a trace; one vanished in May 2010 that was twice as wide as Earth; why? Other surface decors, such as the swirling vortex known as the Great Red Spot, are equally as mysterious: What power source drives their turbulent motion?
For four centuries, astronomers have contemplated Saturn’s eye-popping rings, but none of their attempts to explain the beautiful features have ever seemed quite right. The rings could have formed from the icy remnants of a bygone moon, or from a passing comet torn to shreds by the planet’s gravity; they could be relatively young at just a few hundred million years old, or they might date back to the birth of Saturn more than four billion years ago. We just don’t know. We’re also yet to nail down the dynamics of giant storms and jet streams on the ringed planet’s surface, as well as the dynamics of its rotation.
Planets are expected to radiate heat leftover inside them from their fiery formation process, but puzzlingly, Uranus radiates little or no heat into space. Perhaps the seventh planet’s heat got unleashed during some cosmic smash-up in the distant past. (That collision could also have caused the planet’s strange sideways spin.) Or, maybe Uranus somehow self-insulates, keeping all its heat trapped inside.
Astronomers had expected Neptune to be a weatherless, featureless world in deep freeze. Instead, Voyager 2’s flyby in 1989 — the only close look we’ve ever gotten of this 3-billion-mile-away planet — revealed a turbulent atmosphere with lighter cloud ripples and raging storms. Surprisingly, the fastest winds ever recorded in the solar system whirl on Neptune, up around 1,300 miles (about 2,100 kilometers) per hour. Driving this activity appears to be Neptune’s internal heat, but as the farthest planet from the sun (farthest, that is, ever since the more-distant Pluto was kicked off the planet list in 2006), why does it hold so much heat?
The amateur astronomy community is abuzz over a strange phenomenon spotted over Mars last week. Astrophotographer Wayne Jaeschke reports on his website of a “strange feature” over the Martian plain called Acidalia that moves with the planet and seems to rise over the limb.
The discovery has professional astronomers taking note. NASA’s Mars Odyssey spacecraft will try to image the cloud with a camera that can take pictures in visible and infrared light simultaneously.
Image: A team of volunteers pored over observations from NASA’s Spitzer Space Telescope and discovered more than 5,000 “bubbles” in the disk of our Milky Way galaxy.Credit: NASA/JPL-Caltech/Oxford University
More than 5,000 space bubbles have been discovered in the disk of our Milky Way galaxy by a team of part-time citizen scientists.
These bubbles are blown by young, hot stars into the surrounding gas and dust, and indicate areas of brand-new star formation, scientists say.
“These findings make us suspect that the Milky Way is a much more active star-forming galaxy than previously thought,” Eli Bressert, an astrophysics doctoral student at the European Southern Observatory, said in a statement. “The Milky Way’s disk is like champagne with bubbles all over the place.”
About 35,000 volunteers sifted through data from NASA’s Spitzer Space Telescope on the online Milky Way Project to make the discoveries. These citizen scientists have found about 10 times more bubbles than previous surveys.
Astrophotographer Bill Snyder captured this spectacular view of massive cosmic cloud commonly known as Thor’s Helmet.
Snyder took the image in June 2011 from his home observatory in Connellsville, Penn., and recently provided. Multiple exposures are made to collect enough light for an image that would otherwise not be evident to the eye.
The emission nebula lies in Canis Major, about 15,000 light-years away from Earth. A light-year is the distance light travels in one year, or about 6 trillion miles (10 trillion kilometers).
Fierce stellar winds and intense radiation from a nearby star created the bubble-like shape of the nebula. This star, known as a Wolf-Rayet, is thought to be in a pre-supernova stage and likely has a mass 10 to 20 times that of the sun. The winds from this star create the shell of the glowing nebula. It has a blue-green hue due to the oxygen atoms in the gas.
MUSHROOM LOUD Looking like something from a sci-fi movie, this image, released by NASA, shows the binary star system Eta Carinae as it throws out huge clouds of matter in a non-uniform dumbbell shape — the most detailed and clearest image yet of a dying star. Eta Carinae is one of the closest star systems to Earth that will go supernova in the near future — the “near future” possibly being millions of years from now. (Photo: NASA via the Telegraph)
An uncanny twin of our own Milky Way galaxy takes center stage in a new cosmic portrait by the Hubble Space Telescope unveiled today (Feb. 3).
The amazing photo shows the galaxy NGC 1073, a barred spiral like our own Milky Way. The galaxy is located 55 million light-years away in the constellation of Cetus (The Sea Monster).
By looking at cosmic wonders thought to be similar to our own galactic home, astronomers hope to learn more about the Milky Way, which we can only see from the inside.
The bars, made of dense lines of stars at the galaxies’ centers, are thought to form as gravity causes density waves that push gas inward, supplying material for new stars, Hubble mission researchers explained in a statement. This inflow of gas can also feed the hungry giant black holes thought to inhabit the centers of most such galaxies.
Rocks that fell from the sky and landed in Morocco last summer came from Mars, scientists have confirmed. The meteorite chunks, including one that weighed more than two pounds, rained down in North Africa last July. A special committee of meteorite experts, including some NASA scientists, studied the rocks and determined their origin.
It is only the fifth time in history that experts have been able to confirm by chemical analysis that rocks landing on Earth came from the red planet. Astronomers believe something smashed into Mars millions of years ago and kicked up rock fragments that have been hurtling through the solar system ever since. The landscape in parts of Morocco so resembles that of Mars that rovers destined for the red planet are tested there.