Archives For astronomy

Photo: Saturn’s rings are perhaps the most recognized feature of any world in our solar system. Cassini spent more than a decade examining them more closely than any spacecraft before it. Credit: NASA/JPL-Caltech/Space Science Institute

Saturn’s rings are perhaps the most recognized feature of any world in our solar system. Cassini spent more than a decade examining them more closely than any spacecraft before it. Image Credit: NASA/JPL-Caltech/Space Science Institute

 

October 4, 2018: New research emerging from the final orbits of NASA’s Cassini spacecraft represents a huge leap forward in our understanding of the Saturn system — especially the mysterious, never-before-explored region between the planet and its rings. Some preconceived ideas are turning out to be wrong while new questions are being raised.

Six teams of researchers are publishing their work Oct. 5 in the journal Science, based on findings from Cassini’s Grand Finale. That’s when, as the spacecraft was running out of fuel, the mission team steered Cassini spectacularly close to Saturn in 22 orbits before deliberately vaporizing it in a final plunge into the atmosphere in September 2017.

Knowing Cassini’s days were numbered, its mission team went for gold. The spacecraft flew where it was never designed to fly. For the first time, it probed Saturn’s magnetized environment, flew through icy, rocky ring particles and sniffed the atmosphere in the 1,200-mile-wide (2,000-kilometer-wide) gap between the rings and the cloud tops. Not only did the flight path push the spacecraft to its limits, the new findings illustrate how powerful and agile the instruments were.

Many more Grand Finale science results are to come, but here are some of today’s highlights:

  • Complex organic compounds embedded in water nanograins rain down from Saturn’s rings into its upper atmosphere. Scientists saw water and silicates, but they were surprised to see also methane, ammonia, carbon monoxide, nitrogen and carbon dioxide. The composition of the organics is different from that found on moon Enceladus — and also different from that on moon Titan, meaning there are at least three distinct reservoirs of organic molecules in the Saturn system.
  • For the first time, Cassini saw up close how rings interact with the planet and observed inner-ring particles and gases falling directly into the atmosphere. Some particles take on electric charges and spiral along magnetic-field lines, falling into Saturn at higher latitudes — a phenomenon known as “ring rain.” But scientists were surprised to see that others are dragged quickly into Saturn at the equator. And it’s all falling out of the rings faster than scientists thought — as much as 22,000 pounds (10,000 kilograms) of material per second.
  • Scientists were surprised to see what the material looks like in the gap between the rings and Saturn’s atmosphere. They knew that the particles throughout the rings ranged from large to small. But the sampling in the gap showed mostly tiny, nanometer-sized particles, like smoke, suggesting that some yet-unknown process is grinding up particles.
  • Saturn and its rings are even more interconnected than scientists thought. Cassini revealed a previously unknown electric-current system that connects the rings to the top of Saturn’s atmosphere.
  • Scientists discovered a new radiation belt around Saturn, close to the planet and composed of energetic particles. They found that while the belt actually intersects with the innermost ring, the ring is so tenuous that it doesn’t block the belt from forming.
  • Unlike every other planet with a magnetic field in our Solar System, Saturn’s magnetic field is almost completely aligned with its spin axis. The new data shows a magnetic-field tilt of less than 0.0095 degrees. (Earth’s magnetic field is tilted 11 degrees from its spin axis.) According to everything scientists know about how planetary magnetic fields are generated, Saturn should not have one. It’s a mystery that physicists will be working to solve.
  • Cassini flew above Saturn’s magnetic poles, directly sampling regions where radio emissions are generated. The findings more than doubled the number of direct measurements of radio sources from the planet, one of the few non-terrestrial locations where scientists have been able to study a radio-generation mechanism that is believed to operate throughout the universe.

For the Cassini mission, the science rolling out from Grand Finale orbits more than justifies the calculated risk of diving into the gap — skimming the upper atmosphere and skirting the edge of the inner rings, said Cassini Project Scientist Linda Spilker.

“Almost everything going on in that region turned out to be a surprise,” Spilker said. “That was the importance of going there, to explore a place we’d never been before. And the expedition really paid off — the data is tremendously exciting.”

Analysis of Cassini data from the spacecraft’s instruments will be ongoing for years to come, helping to paint a clearer picture of Saturn.

“Many mysteries remain, as we put together pieces of the puzzle,” Spilker said. “Results from Cassini’s final orbits turned out to be more interesting than we could have imagined.”

The papers published in Science are:

On Oct. 4, as the Science publication embargo lifts, articles describing research complementary to these findings will post online in Geophysical Research Letters (GRL), a journal of the American Geophysical Union (AGU).

Saving the Dark

StephensAstro —  September 2, 2018 — Leave a comment
Photo: The night sky could look like this anywhere in Ohio if we would just be careful with artificial light. Image Credit: "Saving the Dark"

The night sky could look like this anywhere in Ohio if we would just be careful with artificial light. Image Credit: “Saving the Dark”

What do we lose when we lose sight of the stars? Excessive and improper lighting robs us of our night skies, disrupts our sleep patterns, and endangers nocturnal habitats. Saving the Dark explores the need to preserve or restore night skies and what we can all do to combat light pollution. This film will be shown October 5 & 6 at the Chagrin Documentary Film Festival

Click here for more information and to view the film’s trailer.

FINAL — 8:59 PM: Event canceled due to near-Overcast conditions and nearby rain showers. We will try again in July.

UPDATE – June 23, 4:00 PM: Sky conditions are very changeable but prospects look generally poor for tonight’s scheduled Open Night as clouds dominate and isolated showers roam the region. We will make a final go/no-go decision this evening and announce it here and via Twitter.

Stephens Memorial Observatory of Hiram College will be open for public observing Saturday, June 23, from 9:00 to 11:00 PM. Given good skies, visitors will see wonderful views of the Moon and giant planet Jupiter with moons of its own. Other objects of interest, such as star clusters, will also be sought, using the Observatory’s vintage telescope.

Jupiter and Moons - June 23, 2018, 10 PM - Simulated View

Jupiter and Moons – June 23, 2018, 10 PM – Simulated View

The June event represents a late start to our public outreach season caused by an operational problem with the observatory building constructed in 1939. The problem has been corrected and we hope to present a full season’s schedule of public events.

Cloudy skies at the scheduled starting time cancel the event and in that case, the observatory will not open. No reservations are required and there is no admission fee for observatory public nights.

The Observatory is located on Wakefield Road (Rt. 82) less than a quarter of a mile west of Route 700 in Hiram. There is no parking at the Observatory. Visitors may park on permissible side streets near the Post Office, a short distance east of the observatory.

Image: Star π1 Gruis

Astronomers using ESO’s Very Large Telescope have directly observed granulation patterns on the surface of a star outside the Solar System — the ageing red giant π1 Gruis. This remarkable new image from the PIONIER instrument reveals the convective cells that make up the surface of this huge star. Each cell covers more than a quarter of the star’s diameter and measures about 120 million kilometers across. Image Credit: ESO


 
Astronomers using ESO’s Very Large Telescope have for the first time directly observed granulation patterns on the surface of a star outside the Solar System — the ageing red giant π1 Gruis. This remarkable new image from the PIONIER instrument reveals the convective cells that make up the surface of this huge star, which has 700 times the diameter of the Sun. Each cell covers more than a quarter of the star’s diameter and measures about 120 million kilometers across. These new results are being published this week in the journal Nature.

Located 530 light-years from Earth in the constellation of Grus (The Crane), π1 Gruis is a cool red giant. It has about the same mass as our Sun, but is 700 times larger and several thousand times as bright. Our Sun will swell to become a similar red giant star in about five billion years.

An international team of astronomers led by Claudia Paladini (ESO) used the PIONIER instrument on European Southern Observatory’s (ESO’s) Very Large Telescope to observe π1 Gruis in greater detail than ever before. They found that the surface of this red giant has just a few convective cells, or granules, that are each about 120 million kilometers across — about a quarter of the star’s diameter. Just one of these granules would extend from the Sun to beyond Venus. The surfaces — known as photospheres — of many giant stars are obscured by dust, which hinders observations. However, in the case of π1 Gruis, although dust is present far from the star, it does not have a significant effect on the new infrared observations.

When π1 Gruis ran out of hydrogen to burn long ago, this ancient star ceased the first stage of its nuclear fusion program. It shrank as it ran out of energy, causing it to heat up to over 100 million degrees. These extreme temperatures fueled the star’s next phase as it began to fuse helium into heavier atoms such as carbon and oxygen. This intensely hot core then expelled the star’s outer layers, causing it to balloon to hundreds of times larger than its original size. The star we see today is a variable red giant. Until now, the surface of one of these stars has never before been imaged in detail.

By comparison, the Sun’s photosphere contains about two million convective cells, with typical diameters of just 1,500 kilometers. The vast size differences in the convective cells of these two stars can be explained in part by their varying surface gravities. π1 Gruis is just 1.5 times the mass of our Sun but much larger, resulting in a much lower surface gravity and just a few, extremely large, granules.

While stars more massive than eight solar masses end their lives in dramatic supernovae explosions, less massive stars like this one gradually expel their outer layers, resulting in beautiful planetary nebulae. Previous studies of π1 Gruis found a shell of material 0.9 light-years away from the central star, thought to have been ejected around 20,000 years ago. This relatively short period in a star’s life lasts just a few tens of thousands of years – compared to the overall lifetime of several billion – and these observations reveal a new method for probing this fleeting red giant phase.

Photo: StarLab Portable Planetarium

StarLab Portable Planetarium


 
We expect we will cancel our scheduled Friday night Observatory event due to cloudy skies and possible snow. There is, however, a special treat awaiting sky-watchers on campus and it’s indoors, you know, where it’s warm!

The portable StarLab planetarium will be set up and open to the public! Free of charge! No tickets required! Folks can just come any time from 7:00 to 9:00 PM. The more the merrier. We will run 20-minute programs in the dome and have a few things planned while people are waiting or as they leave.

The StarLab will be set up in the Gerstacker science building on the Hiram College campus, not far north of the Post Office: 11700 Dean St.; Hiram.

So, come on out and enjoy a fun and informative evening snug inside StarLab. And to everyone we wish a happy holiday season, as well as peace and happiness in the coming new year!

Photo: Mare Imbrium region of Earth's Moon. Credit: James Guilford/Stephens Memorial Observatory

Mare Imbrium and Crater Copernicus. Credit: James Guilford/Stephens Memorial Observatory

We hosted our September Open Night as scheduled on the 30th with Earth’s Moon as our primary subject. The sky was (for once) completely clear of clouds and full of stars when we opened the dome for the 9:00 start. In all, 19 folks from small children to senior citizens attended and enjoyed spectacular views of our nearest neighbor in space. Two or three individuals attempted smart phone photography of the Moon with varying degrees of success. We also observed the Andromeda Galaxy and the Perseus Double Cluster. The image above was made just before we closed up and has been corrected for the telescope’s optical “flipping” of the image. Camera used was a Canon EOS 7D equipped with a 50mm lens and held to the telescope’s massive eyepiece. We will look at the Moon again October 28 when we celebrate the annual International Observe the Moon Night. See you then?

Photo: The partial solar eclipse reaches its maximum at 2:23 PM EDT as viewed from Hiram College, Hiram, Ohio. Photo by James Guilford.

The partial solar eclipse reaches its maximum at 2:23 PM EDT as viewed from Hiram College, Hiram, Ohio

On Monday, August 21 millions gathered along a thin path crossing the United States to watch a total eclipse of the Sun, the first to cross the continent since June 1918. Those with favorable viewing conditions along the path of totality enjoyed a truly amazing sight and experience; a total solar eclipse is truly awe-inspiring. From Northern Ohio, outside of the eclipse path, 80 percent of the solar disk would be covered by the Moon. Public interest in the event was high and so we hosted the Hiram Eclipse Watch

 

Photo: People Watching and Waiting for the Big Event - Credit: James Guilford

Watching and Waiting for the Big Event – Credit: James Guilford

We estimate at least 375 people came to the campus lawn to share nature’s show and enjoy the sight together. Some families brought blankets and had picnic lunch in the shade of trees while waiting for the eclipse to begin. Driven by media reports, demand for Sun-safe eclipse viewing glasses was tremendous. Hiram had 300 eclipse viewers available for free distribution and even with restriction to one viewer per family or group, we ran out of glasses long before the eclipse ended. The offer of free eclipse glasses did, however, encourage some of our attendees to come out to Hiram College and discover there was more to enjoy than a giveaway; the view through our telescopes was tremendous.

Photo: Woman watches eclipse through specially-equipped telescope. Credit: Dave Dreimiller

Woman watches eclipse through specially-equipped telescope. Credit: Dave Dreimiller

Three telescopes offered safe views of the eclipsing Sun three different ways. One scope employed a glass filter with metal compounds that absorbed the Sun’s dangerous radiation and presented an orange-tinted image. The largest telescope present, a six-inch refractor, was outfitted with a modern version of the Herschel Wedge; that telescope focussed unfiltered light into the wedge which, in turn, deflected all but a small amount of light with a green tint and offered tack-sharp viewing of the disappearing Sun, sunspots, and granulation texture in the solar atmosphere. A third instrument was a telescope specifically made to view the Sun only hydrogen alpha (Ha) light. Ideally, an Hscope will show details of the solar atmosphere invisible to those using other methods, and include solar prominences — geysers of plasma arcing high above the Sun — but none were seen this day.

Photo: Girl Watching the Eclipse with Safety Glasses - Credit: Dave Dreimiller

Watching the Eclipse with Safety Glasses – Credit: Dave Dreimiller

People of all description came and went during the event though most stayed until the maximum eclipse had been reached and the Moon began to recede from Sun. Lines of folks waited patiently to see the telescopic views, even attempting smart phone photos; there were many repeat views, observing the progress of the eclipse with each fresh look. We estimate at more than 375 people came to the campus lawn to share nature’s show and enjoy the sight together.

Photo: Solar Telescopes Trained on the Eclipse - Credit: Dave Dreimiller

Solar Telescopes Trained on the Eclipse – Credit: Dave Dreimiller

There was learning, and laughter, and a fine day shared under Sun and Moon. It may not have been a total eclipse for those watching from Hiram College, but it was a total pleasure.

Photo: Sun in process of being eclipsed by Moon. August 21, 2017. Photo by James Guilford.

Before Maximum Eclipse – Credit: James Guilford

Cooperative weather plus plenty of happy and excited people made the afternoon a wonderful occasion sharing a fine day featuring a dance by the Sun and Moon.

Photo: Edge of lunar silhouette shows mountains on Moon. Photo by James Guilford.

Before Maximum – Rough Edge. Look closely along the dark curve of the Moon moving over the Sun and note “bumps” along the edge: the silhouettes of craters and mountains on the Moon.

The (Ravenna) Record-Courier made it front-page news!

Image: The Record-Courier - August 22, 2017 -- Page 1

The Record-Courier – August 22, 2017 — Page 1