Voyager 2 enters interstellar space

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.

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CAA member photographs Indonesian eclipse

Photo: March 9 Total Eclipse by Steve Korylak
March 9 Total Solar Eclipse by Steve Korylak
CAA member and eclipse chaser Steve Korylak followed the Sun to Indonesia for the March 9 total solar eclipse. He viewed and photographed the event from the deck of a ship positioned for an optimal view of totality. Here are his photographs and his story….

“Not bad for being on a moving ship! The eclipse lasted two minutes, forty seconds; I planned to photograph for one minute, look at the sun visually for one minute and take a movie for the last 40 seconds. I had rehearsed this the day before so I would be prepared. Timing the interval between shots so I did not overload the camera buffer. I had a solar filter on the lens to record the partial phases. Near totality, I looked for shadow bands on the side of the white ship and did not see them. When I took off the filter the focus changed, even though I had it taped so it would not move; this caused me to miss the diamond ring and bailey’s beads. I had to refocus — still slightly off — and started taking pictures. Then the eclipse was over; no visual, no movie. Learning experience!”

Photo Info: Inner corona – Nikon D1500 (APS-size sensor) 1/4000 sec., f/11, ISO 1000, 300mm lens with 2X teleconverter. Outer  corona – same hardware, 1/60 sec., f/11, ISO 1000. The lens was f/5.6 but with the teleconverter it is equivalent to f/11. shot in raw mode for maximum detail.

Photo: March 9 Total Solar Eclipse by Steve Korylak
March 9 Total Solar Eclipse by Steve Korylak – Note Red Prominences over the Sun’s Limb

There’s a big black spot on the Sun today

Photo: Sun with sunspot AR2529, April 13, 2016. Photo by James Guilford.
Sunspot AR2529

Changing a word from an old Police lyric, there’s a big black spot on the Sun today. Sunspot AR2529 is the dominant feature on an otherwise quiet star. Visible to the unaided eye through solar-safe filters, the sunspot is several Earth-diameters across and roughly “heart” shaped! This image was recorded Wednesday, April 13, at 2:19 PM. The bright orange color resulted from use of a solar filter covering the camera lens.

Here is what SpaceWeather.com says about the sunspot: “Since it appeared less than a week ago, AR2529 has been mostly, but not completely, quiet. On April 10th it hurled a minor CME into space. That CME, along with another that occurred a few hours later, could deliver a glancing blow to Earth’s magnetic field on April 13th.” A CME is a Coronal Mass Ejection wherein the Sun flings plasma from its atmosphere out and into space. CMEs reaching Earth can cause auroras.

Photo Info: Cropped from full frame, Canon EOS M3: ISO 250, 1/1600 sec., f/8, 400mm lens. Photo by James Guilford.

Sun lights up day and night (some places) in early November

Photo: Train of Sunspots, November 4, 2105. Photo by James Guilford.
Train of Sunspots, November 4, 2015. Credit: James Guilford

An impressive train of sunspots has been making its way across the face of our nearest star this week. In the photo above: Designated AR2447 (small group to the left), AR2443 (bigger and darker, near center), and AR2445 (far right), the “Active Regions” have the potential of unleashing flares. In fact, AR2445 was the source of a flare that caused this week’s “northern lights” sighted across northern latitude locations around the world. Now rotating over the Sun’s limb, AR2445 won’t be aimed at Earth for a while — if ever again — but AR2443 has potential for high-energy flares.

Photo credit: James Guilford. Canon EOS 7D II: ISO 400, f/11, 1/1250 sec., 400mm lens with Astrozap film solar filter, heavily cropped, November 4, 2015.

Auroras delight night owls

Photo: Auroral display over Lake Erie. Photo by Christopher Christie.
Auroral display over Lake Erie. Photo by Christopher Christie.

A group of CAA members took advantage of beautiful night sky conditions to set up and observe from Medina County Parks’ Letha House Park — site of our Observatory. Among them was Christopher Christie. “I got home about 2:00 AM after a great, but cold night out at Letha House” he wrote. “I was starting to wind down around 3:00 AM when I noticed the Kp index was kicking up as the solar wind increased, it wasn’t much at the time but I kept an eye on it.”

He kept tabs on the situation. “About 3:30 the KP was up at 6, so I went to my front porch and didn’t see anything, but checked some of the other sites I use to check on the aurora and one showed a possibility of some moving in. So I went to the lake shore just inside Rocky River, and, well after about an hour and 175 images or so I was very happy.” We’re pretty pleased to see his results.

Auroral display over Lake Erie. White light at left-horizon is a passing boat. Photo by Christopher Christie.

It turns out Christie had tapped into the beginning of a big geomagnetic storm. By Saturday afternoon SpaceWeather.com was reporting that the storm continued to light the skies over nighttime areas of the globe and was expected to be active through Saturday night. Of course Saturday night brought clouds and rain to the Greater Cleveland Area. Still, it was a noteworthy event.

SpaceWeather.com explained, “The ongoing storm was triggered by a knot of south-pointing magnetism from the sun. During the early hours of Oct. 13, the knot bumped into Earth’s magnetic field, opening a crack in our planet’s magnetosphere. Solar wind poured in to fuel the auroras.”

Green flash puts in an appearance over Lake Erie

Photo: Sunset with possible green flash. Credit: Jay Reynolds
At the bottom edge of the setting Sun, here, there may be a green flash.

The “green flash” is not a new Marvel Comics superhero but a subtle and interesting phenomenon sometimes seen just before sunrise or just after sunset; a green-colored ray or spot is seen just above the horizon. CAA member Jay Reynolds observed and photographed an occurrence of the green flash on Aug. 6 from Kelleys Island.

“Unfortunately, as these predictions go, the possibility of seeing it was well announced by TV meteorologists…” said Reynolds, “but this occurrence was subtle and not easily detectable.” In other words, many looked for the flash but few saw it!

“In photo number one, there is a possible green flash visible at the bottom of the sun. It is unfortunate that the shot is overexposed to the point of saturation” he said. “Suzie Dills deserves the credit for detecting it during the photo review.”

Photo: Green flash is visible just after sunset August 6, 2012. Credit: Jay Reynolds
Green flash is visible just after sunset August 6, 2012. Enlarge to best see color.

“Photo number two is the best of the main sequence,” said Reynolds of his images. Viewed in a larger size, the green coloration is easily visible.

“It still was an outstanding Lake Erie Sunset shared by all!”

Photo credit: Jay Reynolds.

Big sunspot takes aim at Earth

Photo: The Sun with sunspots July 12, 2012. Photo by James Guilford.
Just below center-left, is AR1520, as seen from Northeastern Ohio on July 12 at 6:18 PM EDT.

Dominating the face of our Sun, this week, has been an enormous group of sunspots including those designated AR1520. The active Sun has been very interesting to watch, of late, as the dark spots rotated over the star’s limb and towards the center of its disk, facing Earth. Hydrogen-alpha observers have also been rewarded with good numbers of prominences spouting into the blackness of space. Forecasters stated AR1520 had great potential for flare activity and on Thursday, July 12, the forecast was fulfilled — just as the sunspot was aimed directly at Earth.

According to SpaceWeather.com, “Big sunspot AR1520 unleashed an X1.4-class solar flare on July 12th at 1653 UT. Because this sunspot is directly facing Earth, everything about the blast was geoeffective. For one thing, it hurled a coronal mass ejection (CME) directly toward our planet. According to a forecast track prepared by analysts at the Goddard Space Weather Lab, the CME will hit Earth on July 14th around 10:20 UT (+/- 7 hours) and could spark strong geomagnetic storms. Sky watchers should be alert for auroras this weekend.”

NASA’s orbital solar observatories, of course, captured images of the flare as it erupted. Very rarely is any individual human observer watching when the detonation occurs but one can get lucky. CAA Vice-President Mike Williams was very lucky. “I was looking at the spot {with my personal solar telescope} when it popped,” he said. “Wow what a sight!”

As so often seems the case, weather forecasts for the weekend include plenty of clouds to interfere with the view. Still, aurora fans should stay alert to active displays and the potential for clear skies; it could be a good show!

UPDATE: The CME impacted the Earth’s magnetic field at ~ 1800 UT or 2:00 PM EDT, July 14.

Photo above: The Sun with prominent AR1520 accompanied by smaller sunspots. Canon EOS 50D: ISO 400, f/11, 1/1000 sec., 400mm telephoto lens with AstroZap white light filter, 6:18 PM, July 12, 2012 — “just before the clouds rolled in,” according to photographer James Guilford.