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How I Discovered Halley’s Comet, by Edmond Halley

On Monday, June 10, in the Evening, the Sky being very serene and calm, I was desirous to take a view of the disk of Mars (then very near the Earth, and appearing very glorious) to see if I could distinguish in my 24 Foot Telescope, the Spots said to be seen on him. Directing my Tube for the purpose, I accidentally fell upon a small whitish Appearance near the Planet, resembling in all respects such a Nebula … The Reverend Mr. Miles Williams, Mr. Alban Thomas, and myself contemplated this Appearance for above an Hour … and we could not be deceiv’d as to its Reality; but the slowness of its Motion made us at that time conclude that it had none, and that it was rather a Nebula than a Comet.

Read more. [Image: Wikimedia Commons]

Saturn,cassini

Johannes Hevelius, Cometographia (Danzig, 1668), Fig. L

ASTRONOMERS CAPTURE BEST VIEW EVER OF DISINTEGRATING COMET

Astronomers have captured the sharpest, most detailed observations of a comet breaking apart 67 million miles from Earth, using NASA’s Hubble Space Telescope. The discovery is published online today in Astrophysical Journal Letters [http://apjl.aas.org].

In a series of images taken over three days in January 2016, Hubble showed 25 fragments consisting of a mixture of ice and dust that are drifting away from the comet at a pace equivalent to the walking speed of an adult, said David Jewitt, a professor in the UCLA departments of Earth, Planetary and Space Sciences; and Physics and Astronomy, who led the research team.

The images suggest that the roughly 4.5-billion-year-old comet, named 332P/Ikeya-Murakami, or Comet 332P, may be spinning so fast that material is ejected from its surface. The resulting debris is now scattered along a 3,000-mile-long trail, larger than the width of the continental United States.

These observations provide insight into the volatile behavior of comets as they approach the Sun and begin to vaporize, unleashing powerful forces.

“We know that comets sometimes disintegrate, but we don’t know much about why or how,” Jewitt said. “The trouble is that it happens quickly and without warning, so we don’t have much chance to get useful data. With Hubble’s fantastic resolution, not only do we see really tiny, faint bits of the comet, but we can watch them change from day to day. That has allowed us to make the best measurements ever obtained on such an object.”

The three-day observations show that the comet shards brighten and dim as icy patches on their surfaces rotate into and out of sunlight. Their shapes change, too, as they break apart. The icy relics comprise about four percent of the parent comet and range in size from roughly 65 feet wide to 200 feet wide. They are separating at only a few miles per hour as they orbit the Sun at more than 50,000 miles per hour.

The Hubble images show that the parent comet changes brightness frequently, completing a rotation every two to four hours. A visitor to the comet would see the Sun rise and set in as little as an hour, Jewitt said.

The comet is much smaller than astronomers thought, measuring only 1,600 feet across, about the length of five football fields.

Comet 332P was discovered in November 2010, after it surged in brightness and was spotted by two Japanese amateur astronomers.

Based on the Hubble data, the research team suggests that sunlight heated the surface of the comet, causing it to expel jets of dust and gas. Because the nucleus is so small, these jets act like rocket engines, spinning up the comet’s rotation, Jewitt said. The faster spin rate loosened chunks of material, which are drifting off into space. The research team calculated that the comet probably shed material over a period of months, between October and December 2015.

Jewitt suggests that some of the ejected pieces have themselves fallen to bits in a kind of cascading fragmentation. “We think these little guys have a short lifetime,” he said.

Hubble’s sharp vision also spied a chunk of material close to the comet, which may be the first salvo of another outburst. The remnant from still another flare-up, which may have occurred in 2012, is also visible. The fragment may be as large as Comet 332P, suggesting the comet split in two. But the remnant wasn’t spotted until Dec. 31, 2015, by a telescope in Hawaii.

That discovery prompted Jewitt and colleagues to request Hubble Space Telescope time to study the comet in detail.

“In the past, astronomers thought that comets die when they are warmed by sunlight, causing their ices to simply vaporize away,” Jewitt said. “But it’s starting to look like fragmentation may be more important. In comet 332P we may be seeing a comet fragmenting itself into oblivion.”

The researchers estimate that comet 332P contains enough mass for 25 more outbursts. “If the comet has an episode every six years, the equivalent of one orbit around the Sun, then it will be gone in 150 years,” Jewitt said. “It’s just the blink of an eye, astronomically speaking. The trip to the inner solar system has doomed it.”

The icy visitor hails from the Kuiper belt, a vast swarm of objects at the outskirts of our solar system. As the comet traveled across the system, it was deflected by the planets, like a ball bouncing around in a pinball machine, until Jupiter’s gravity set its current orbit, Jewitt said.

Fading Females

As the daughter of our town’s E.S.D.A. Coordinator, I have always been intrigued by ham radio. My father (and elmer) has been a ham for about 40 years. He actually received his license when he was in high school!

After studying for three weeks, I went to take the ham test. I was very discouraged to see that I was the only girl in the room. However, I was treated like a queen by the group that was hosting the test. They seemed excited to have a female in their midst.

Upon receiving my Technician license, I eagerly awaited the Tuesday night ARES net (which my dad happens to be the Net Control of). Again, I was saddened to hear but a few female voices. Over time, I noticed that the female hams rarely checked in to the net. I wondered why these women who worked so hard to achieve their licenses would not want to take advantage of all that ham radio has to offer.

I hope that women are being encouraged to be active hams. Whether they join a club or simply make contacts, females are providing a fresh voice and perspective to the hobby. So, ladies, do not be shy! Proudly check in with your call sign. You have earned it!

NASA Tests 3-D Printed Engine Components

3-D printing isn’t just for toys and plastic models of your head. Witness a hot fire of NASA’s newest design for rocket engine injectors, 3-D printed to up performance in a way that traditional manufacturing of the parts couldn’t attain.

The agency, which tested the experimental injectors last month at Marshall Space Flight Center in Huntsville, Ala., used a type of 3-D printing called direct laser melting. To make the parts, a machine fires a laser at metal powder under the direction of a computer design program. This deposits layers of the metal one on top of the other until the part is complete.

NASA says the technique is letting engineers build the injector out of just two parts instead of the 163 formerly needed using traditional manufacturing methods.

Keep reading

Cassini gets up close & personal with icy Mimas

The first two images show off the giant Herschel crater, a distinguishing feature of this moon. The second gives a better view of the mountain peak within the crater. The shadows cast by the crater and mountain peak give a glimpse into just how massive this crater truly is. The last image is one of the clearest images of Mimas to date.

on Nov. 28, 2013, comet ISON will fly through the sun’s atmosphere little more than a million km from the stellar surface. If the comet survives without breaking up it could emerge glowing as brightly as the Moon, visible near the sun in broad daylight.

Kindly share this, so that no one could miss that event!

Imagine a messy clump not unlike the hair clogging your sink, only on a celestial scale. This wad of soggy detritus sits way out in the Kuiper belt, where Pluto and other small, icy bodies hang out. Also, the mysterious clump in question consists of said icy objects and not actual hair. This would be a very different entry otherwise.

Scientists weren’t quite sure what caused this, so they started running computer simulations of different things that might make them clump in the observed way. In January 2016, they published a paper presenting a potential cause for the phenomenon: a hitherto undiscovered giant of a planet, 10 times the size of Earth, skulking all but silently about the edges of our solar system like a cosmic Hodor.

Arguments for and against the theory are ongoing and just so, so dorky – but computer simulations certainly do support the idea that a large planet could be causing these groupings to occur. So we might have a whole new planet! Your outdated knee-jerk answer of “nine” when somebody asks how many planets are in our solar system may once again be correct!

5 Mysteries About Space That Might Have Horrifying Answers