November 11 Membership Meeting: “Catching the Sun…”

In its prime, the McMath-Hulbert Observatory shone in the sun, circa 1941. Credit: University of Michigan and McMath-Hulbert Observatory

The final Membership Meeting of the Cuyahoga Astronomical Association (CAA) for 2019 will take place Monday, November 11. The meeting will feature a presentation by member Steve Gallant entitled, “Catching the Sun: Robert McMath and the McMath-Hulbert Solar Observatory.”

Located north of Pontiac, Michigan and opened in 1929, after the initial attempts to study the moon, the main preoccupation of the observatory was the sun. McMath-Hulbert was once the second largest solar observatory in the world. Spears will fill us in on the observatory’s history and the current efforts to preserve and promote its continued use!

The CAA’s monthly meetings are held on the second Monday of every month except December at 7:30 p.m. in the Rocky River Nature Center; 24000 Valley Parkway; North Olmsted, Ohio, in the Cleveland Metroparks. Meeting programs are open to the public. Following the presentation and a brief social break, the club will conduct its membership business meeting.

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.

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 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.