Image: This illustration shows the position of NASA’s Voyager 1 and Voyager 2 probes, outside of the heliosphere, a protective bubble created by the Sun that extends well past the orbit of Pluto. Credits: NASA/JPL-Caltech

This illustration shows the position of NASA’s Voyager 1 and Voyager 2 probes, outside of the heliosphere, a protective bubble created by the Sun that extends well past the orbit of Pluto. Credits: NASA/JPL-Caltech

 
For the second time in history, a human-made object has reached the space between the stars. NASA’s Voyager 2 probe now has exited the heliosphere – the protective bubble of particles and magnetic fields created by the Sun.

Comparing data from different instruments aboard the trailblazing spacecraft, mission scientists determined the probe crossed the outer edge of the heliosphere on Nov. 5. This boundary, called the heliopause, is where the tenuous, hot solar wind meets the cold, dense interstellar medium. Its twin, Voyager 1, crossed this boundary in 2012, but Voyager 2 carries a working instrument that will provide first-of-its-kind observations of the nature of this gateway into interstellar space.

Voyager 2 now is slightly more than 11 billion miles (18 billion kilometers) from Earth. Mission operators still can communicate with Voyager 2 as it enters this new phase of its journey, but information – moving at the speed of light – takes about 16.5 hours to travel from the spacecraft to Earth. By comparison, light traveling from the Sun takes about eight minutes to reach Earth.

The most compelling evidence of Voyager 2’s exit from the heliosphere came from its onboard Plasma Science Experiment (PLS), an instrument that stopped working on Voyager 1 in 1980, long before that probe crossed the heliopause. Until recently, the space surrounding Voyager 2 was filled predominantly with plasma flowing out from our Sun. This outflow, called the solar wind, creates a bubble – the heliosphere – that envelopes the planets in our solar system. The PLS uses the electrical current of the plasma to detect the speed, density, temperature, pressure and flux of the solar wind. The PLS aboard Voyager 2 observed a steep decline in the speed of the solar wind particles on Nov. 5. Since that date, the plasma instrument has observed no solar wind flow in the environment around Voyager 2, which makes mission scientists confident the probe has left the heliosphere.

“Working on Voyager makes me feel like an explorer, because everything we’re seeing is new,” said John Richardson, principal investigator for the PLS instrument and a principal research scientist at the Massachusetts Institute of Technology in Cambridge. “Even though Voyager 1 crossed the heliopause in 2012, it did so at a different place and a different time, and without the PLS data. So we’re still seeing things that no one has seen before.”

In addition to the plasma data, Voyager’s science team members have seen evidence from three other onboard instruments – the cosmic ray subsystem, the low energy charged particle instrument and the magnetometer – that is consistent with the conclusion that Voyager 2 has crossed the heliopause. Voyager’s team members are eager to continue to study the data from these other onboard instruments to get a clearer picture of the environment through which Voyager 2 is traveling.

“There is still a lot to learn about the region of interstellar space immediately beyond the heliopause,” said Ed Stone, Voyager project scientist based at Caltech in Pasadena, California.

“Voyager has a very special place for us in our heliophysics fleet,” said Nicola Fox, director of the Heliophysics Division at NASA Headquarters. “Our studies start at the Sun and extend out to everything the solar wind touches. To have the Voyagers sending back information about the edge of the Sun’s influence gives us an unprecedented glimpse of truly uncharted territory.”

While the probes have left the heliosphere, Voyager 1 and Voyager 2 have not yet left the solar system, and won’t be leaving anytime soon. The boundary of the solar system is considered to be beyond the outer edge of the Oort Cloud, a collection of small objects that are still under the influence of the Sun’s gravity. The width of the Oort Cloud is not known precisely, but it is estimated to begin at about 1,000 astronomical units (AU) from the Sun and to extend to about 100,000 AU. One AU is the distance from the Sun to Earth. It will take about 300 years for Voyager 2 to reach the inner edge of the Oort Cloud and possibly 30,000 years to fly beyond it.

Photo: Earth's Moon two days short of Full. Photo by James Guilford.

CANCELED: Skies will remain cloudy through Saturday and into Sunday with a chance of snow showers. Also, streets in Hiram Village have been stripped for resurfacing and present challenges to parking. We can’t catch a break this year, it seems. Tonight’s scheduled Open Night is CANCELED and the observatory WILL NOT be open. — Saturday, Nov. 17.

UPDATE: It appears that, yet again, we will need to cancel our scheduled Open Night event due to sky conditions and weather! We will post a final update here Saturday afternoon regarding the status of the evening’s event. — Friday, Nov. 16.

Stephens Memorial Observatory of Hiram College will host a Public Night Saturday, November 17, from 7:00 to 9:00 PM. On the observing list are the Moon, the Pleiades and Perseus Double star clusters, a farewell look at Mars, and a possible peek at planet Neptune. Other objects of interest may also be viewed.

Organizers hope for clear skies since several recent events have been canceled or compromised by weather. Visitors will be able to view planetary and celestial objects using the Observatory’s 1901 vintage telescope as well as stunning views of Earth’s Moon.

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.

Updates on programming are available via the Observatory’s Twitter feed: @StephensObs (twitter.com/StephensObs)

International Observe the Moon Night, October 20, 2018

 

UPDATE: Saturday, October 20 — Tonight’s scheduled Open Night and local International Observe the Moon Night event is CANCELED. Weather again spoils our plans with showers and thunderstorms prowling the area, and tonight’s impending Wind Advisory keeping our dome closed. While weather is going to keep us indoors tonight, NASA has other suggestions on how you can observe and enjoy Earth’s Moon tonight and later! Take a look: Ten Ways to Observe the Moon, Some Can be Done Any Time

UPDATE: We are closely watching weather forecasts and, as so often has been the case this year, our Saturday night program appears in jeopardy with the possibility of rain and/or snow predicted. Check back here and watch our Twitter feed for further updates and a final go/no-go decision on our October 20 event.

Members of the public are invited to celebrate International Observe the Moon Night on Saturday, Oct. 20 from 7:00 to 9:00. The free event will be held at Stephens Memorial Observatory of Hiram College.

International Observe the Moon Night is an annual worldwide public event that encourages observation, appreciation and understanding of our Moon and its connection to NASA planetary science and exploration. The annual event connects scientists, educators, and lunar enthusiasts from around the world.

The Hiram event will (given clear skies) include amazing views of Earth’s Moon using the Observatory’s 1901 vintage telescope. If sky conditions allow, other wonders of the night sky will also be sought.

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.

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).

UPDATE: 8:30 PM — CLOSED. We give up! 😕Although some clearing is expected later, skies will not be adequate to our Public Night needs. The observatory will not be open.

UPDATE: 3 PM — Again we struggle with cloudy skies! Predictions for tonight’s sky range from partly- to mostly-cloudy with seeing conditions rated as fair to poor. If we do open for tonight’s scheduled Public Night, we will doubtless offer only a limited program, perhaps only the Moon and Mars; dimmer objects won’t be seen. Please check back this evening or follow our Twitter feed for further updates. https://twitter.com/StephensObs

Stephens Memorial Observatory of Hiram College will be open for public observing Saturday, September 22, from 9:00 to 11:00 PM. Organizers are hoping for clear skies in order to provide visitors with views of the Moon, Red Planet Mars, the Andromeda Galaxy, and a star cluster using the Observatory’s vintage telescope. Weather forecasts (September 20) call for partly-cloudy skies and we will hope for clear air between those clouds; our last public viewing endured mostly-clear skies marred by moonlit smoke from California wildfires high in the atmosphere!

Sadly, a comet, originally expected to be visible, has moved below our horizon and will not be on our agenda.

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.

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.

Illustration: Saturn and Some Moons as they will appear at 10 PM, August 18, 2018. Simulation by Gas Giants.

Saturn and Some Moons as they will appear at 10 PM, August 18, 2018. Simulation by Gas Giants.

UPDATE: Thank you to the 38 folks who came out to visit us tonight and enjoy the view – such as it was! Early arrivals had exquisite views of Earth’s Moon; then nice views of Saturn with pastel cloud bands across the planetary body and the Cassini Division visible. Late comers got respectable views of Mars though the Martian dust storm hid details! Unfortunately, atmospheric haze/clouds hid the northern sky from us preventing views of the night’s comet and other wonders. Thanks for your patience, kind visitors, and we will hope for truly clear skies in September!

Stephens Memorial Observatory of Hiram College will be open for public observing Saturday, August 18, from 9:00 to 11:00 PM. Organizers are hoping for clear skies in order to provide visitors with wonderful views of the Moon, Red Planet Mars, and the “ring world” Saturn using the Observatory’s vintage telescope. With clear enough skies, and a little luck finding it, viewers may also have the opportunity to view Comet 21P/Giacobini–Zinner which is currently dim and with only the hint of a tail.

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.