Category Archives: lectures

An evening with famed comet hunter Don Machholz

In an age when automated programs are scanning the night sky using high-tech telescopes, CCD cameras, and computing power to find near-Earth objects, Don Machholz continues to search for comets the old-fashioned way.

“I do it visually,” Machholz explained at the annual banquet of the Seattle Astronomical Society last month. “I do not use cameras, I do not use CCDs. I look through the eyepiece and I push the telescope.”

Scheiderer and Machholz

Seattle Astronomy’s Greg Scheiderer, left, with comet hunter Don Machholz at the Seattle Astronomical Society’s annual banquet. Photo: Greg Scheiderer.

Machholz is the record holder, with eleven comets discovered visually since he started his hunt in the mid-1970s. That doesn’t sound like so many, but consider this: according to the Catalog of Comet Discoveries, there have been 1,502 comets discovered since 2005. Of those, just three have been discovered visually. The Panoramic Survey Telescope & Rapid Response System (Pan-STARRS) got full or shared credit for thirty-three comet discoveries last year alone. The last time a comet was discovered visually was in 2010, when there were two, and Machholz bagged one of those.

There’s a little bit of luck involved in comet hunting. Machholz jokes that the first thing you need to do to find a comet is to be looking where it is in the 40,000 square degrees of sky. But he has a system. He checks websites to figure out where the programs like Pan-STARRS are looking on a particular night and then conducts his hunt in a different part of the sky. Machholz divides the sky into sections, and makes telescope sweeps covering about fifteen degrees at a time. Then moves down about a half field of view and sweeps again. He keeps meticulous records of his searches.

“It sounds boring, but you get to see a different part of the sky all the time,” Machholz said.

He got interested in astronomy as a boy. His father was a naval navigator and had a book with star charts that Don used to learn the sky. When he was about eight years old his sister brought home a book about meteors that piqued his interest. Finally, Machholz received a telescope for his thirteenth birthday. On the third night out he found Saturn.

“I could see the rings on it,” he recalled, thinking stargazing might not be such a bad hobby. He was hooked.

A family tragedy helped drive Machholz’s comet-hunting program early on. In 1976 his brother, an avid skier, was killed in an avalanche. Machholz found himself depressed, with insomnia, sleeping just a few hours a night, but with lots of energy.

“That’s kind of the ideal ingredients for a comet hunter,” he said. “For the next three or four years my comet hunting program developed to a greater and greater depth. Comet hunting wasn’t just something I did, it became part of who I am.”

His early comet hunting was done from his parents’ back yard and other locations around Concord, California. After moving to San Jose in 1976 he did much of his observing from nearby Loma Prieta mountain. In 1990 he moved to Colfax, California and built an observatory there.

After so much time at the eyepiece, Machholz says his heart still skips a beat or two when he thinks he has found a new comet.

“It’s a very important moment,” he said. “First I want to remember what song was on the radio.” He always has the radio playing when he hunts, and his presentation was full of music from the Rolling Stones and the Beatles to Phil Collins and Cyndi Lauper. He adds, though, that there’s no time for jumping up and down when he finds a comet, because there’s serious work to do.

“You don’t want to lose it,” he explained. “You might have it in the field now, but if you bump the telescope or let too much time go by and it drifts out of the field, you have to be able to find it again.”

“You have to be sure you know where you’re looking, make sure it’s not a galaxy or a cluster,” he added. He double checks with his star atlas, makes a drawing that puts the comet in its position compared to the field of stars, and watches to see if it moves. If all that checks out he reports the discovery by email, phone, and fax.

96/P Machholz

Comet 96/P Machholz as seen by the HI-2 camera on the STEREO-A spacecraft.

Of all of his discoveries, Machholz said comet is 96P/Machholz is his favorite.

“It is an amazing comet; it has its own Facebook page,” he said.

The orbit of 96/P Machholz changes because of the influence of Jupiter, and the perturbations have some scientists thinking there may be large undiscovered planets way out beyond Pluto. The comet also is low on carbon and cyanogen. This hasn’t been explained, though the leading ideas are that it may have originated in another solar system, or been exposed to temperature extremes that changed its chemical composition.

It was a pleasure to spend an evening with Don Machholz. His lively presentation was full of humor and had the banquet audience laughing and engaged.

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Rosetta mission: the end of the beginning

There have been a lot of amazing space missions that rank among the greatest engineering achievements of all time. The Rosetta mission has to be one of the most impressive ever. Rosetta traveled 10 years and more than four billion miles to rendezvous with comet 67P/Churyumov-Gerasimenko, a rubber-ducky-shaped pile of rocks 2.5 miles across that is zipping through space at about 84,000 miles an hour. It went into orbit around the comet and then it dropped a lander, Philae, that touched down on the surface of the comet back in November. Never mind that Philae didn’t stick the landing; that’s an quite an accomplishment.

Paul Weissman

Paul Weissman of JPL spoke about the Rosetta mission Monday at the 225th meeting of the American Astronomical Association.

Thus it was most enjoyable to hear from one of the Rosetta mission scientists, Paul Weissman of the NASA Jet Propulsion Laboratory, on Monday afternoon at the 225th meeting of the American Astronomical Society. Weissman gave a talk titled “Back to the Beginning: The Rosetta Mission to Comet Churyumov-Gerasimenko.”

“Doing space missions is a work of delayed gratification,” Weissman quipped, noting that they actually started work on Rosetta in 1996, and adding that there had been plans for such a mission for about a decade before that. They finally launched in 2004 and arrived at the comet, often shortened to C-G for obvious reasons, back in August.

“We had been ten years in space,” Weissman said. “It was really exciting to finally arrive at the comet.”

Rosetta carries 11 scientific instruments on board, and the Philae has ten. Even though Philae didn’t operate for long, between them the two craft have sent back a wealth of data.

“We’ve just been flooded with phenomenal results,” Weissman said.

Philae on C-G

Rosetta’s lander Philae on the surface of Comet 67P/Churyumov-Gerasimenko. One of the lander’s three feet can be seen in the foreground. The image is a two-image mosaic. Credit: ESA/Rosetta/Philae/CIVA

He shared a great many photographs from the mission and explained what all of the instruments have been observing. Among the interesting discoveries are that C-G is spinning faster than it did on its previous trip around the Sun, the result of the forces of outgassing of the comet’s material. There are pits on the nucleus that may be sink holes or outbursts; they’re not quite sure yet. They’ve detected water within the comet, and learned it is colder in its interior than on the surface. And the comet has about 74 percent porosity.

Some of the most fantastic returns are images taken by Philae from the surface of C-G that show exquisite detail.

“We’re looking at millimeter resolution of the surface of the comet,” Weissman noted, “something that’s just astounding in terms of what we’ve been able to do previously.”

Weissman holds out hope that they’ll get more from Philae, even though its batteries are dead because it landed in the shade.

“It may be possible to re-awaken the lander in May of this year,” he noted. “The solar panels that are exposed will gather enough energy to charge up the batteries, and we might have another shot of making measurements with the lander.”

Whether that works or not, there already is a great deal of data that mission scientists simply have not yet had time to analyze, and there’s more to come.

“This is the end of the beginning,” Weissman said, “because we have another whole year that we’re going to be in orbit, studying the nucleus and watching it get active. It reaches perihelion in August, so we’ll also watch it get inactive. And there’s talk of an extended mission into 2016.”

“This is just a remarkable mission.”

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A dim view of the future of funding for space exploration

Dr. John M. Logsdon does not paint a very optimistic picture of the future of funding for space exploration. Logsdon, considered the dean of space policy and the founder of the Space Policy Institute at George Washington University, gave a talk titled “What Do We Expect of a Space Program?” today at the 225th meeting of the American Astronomical Society in Seattle.

John Logsdon

Dr. John Logsdon speaking Jan. 5, 2015, at the 225th meeting of the American Astronomical Society in Seattle.

Logsdon pulled the title of his lecture from a line in a Nixon Administration memo about the future of the space program. He says a big part of the problem is that, in more than four decades since the memo, the underlying question has not been adequately answered.

Logsdon pins much of the blame for the situation on President Nixon, who scaled back funding for NASA after the race to the Moon was won.

“The decisions he made from the ’69 through ’71 period, culminating in the January 5, 1972 announcement of the approval of the space shuttle, really characterized the program that NASA executed for the next 40-plus years, and basically avoided answering the question ‘What do we expect?’ by developing capabilities rather than seeking goals,” Logsdon said.

We had the answer under President Kennedy, according to Logsdon, when the goal was not just to put people on the Moon, but to achieve preeminence about all things in outer space.

“What is distinctive about Kennedy is he not only talked the talk, but he walked the walk,” Logsdon said. “He made a commitment of human and financial resources, peaceful but warlike mobilization of resources, to carry out that program of preeminence.”

Logsdon pointed out that the budget for NASA was $964 million when JFK urged the US to go the Moon; it had ballooned to $5.2 billion by 1965. Space science shared in the growth, its part of the NASA budget going from $131 million to $767 million in the same time frame.

Logsdon is tackling the history of presidential support for space exploration in his scholarship. He published John F. Kennedy and the Race to the Moon in 2010. His new book, After Apollo?: Richard Nixon and the American Space Program, is due out in March. The latter goes into great detail about Nixon’s approach and its lasting impact.

While NASA’s budget has fluctuated over the years, Logsdon sees a silver lining in the nation’s investment in science.

“The ups and downs in the overall NASA budget are not reflected in the budget for space science, which has shown a rather gradual but steady increase for the past 25 or 30 years, and has not vacillated,” he said. “Compared to the human spaceflight part of NASA, the space science, robotic science program, including Earth science, is in pretty good shape and is not being argued about.”

Logsdon served on the Columbia Accident Investigation Board, which opined in 2003 that NASA was being forced to do too much without adequate resources. He said that’s still a problem. The reason he doesn’t see a good solution ahead is that there are three possible responses, two of which he views as unlikely. He doesn’t foresee a great increase in our ambitions or some Sputnik-like incident that creates urgency about space. Nor does he anticipate a significant increase in spending, though that could depend in part on who the next president turns out to be.

“The most likely outcome is that we just keep muddling along, as we have since 1971, with a suboptimal program,” he concluded.

Further reading:

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Shields up! Scientists find impenetrable barrier around Earth

Planet Earth has an invisible and impenetrable shield about 7,200 miles out in space that blocks killer electrons from coming in and zapping satellites and causing all sorts of other havoc in the wake of huge coronal mass ejections from the Sun. This barrier is a major discovery of the Radiation Belt Storm Probe and the Relativistic Electron Proton Telescope (REPT), launched by NASA in August of 2012.

Baker

Dr. Daniel Baker

Dr. Daniel Baker, REPT science lead at the Laboratory for Atmospheric and Space Physics at the University of Colorado, spoke about the mission and the discoveries today during his opening lecture at the 225th meeting of the American Astronomical Association in Seattle. The discoveries were detailed in an article in Nature back in November.

Baker has some great credentials for the project. He earned his Ph.D. under James Van Allen, whose gear first detected the Van Allen Belts—he preferred to call them zones—in 1957, in what many consider to be the first major scientific discovery of the space age. Baker also was an investigator on SAMPEX, a particle exploring mission that operated from 1992 until 2004.

There are twin REPT probes in a highly elliptical orbit around the Sun. One of the first major discoveries by REPT, according to Baker, was of a third Van Allen Belt, a storage belt of ultra-relativistic particles that remains constant while the other belts vary wildly because of solar events.

Interestingly enough, these particles don’t ever get in any closer than about 2.8 Earth radii. Baker says that was a strange discovery, as nature typically doesn’t like such sharp barriers, but observations so far have shown it to be an impenetrable.

“It looks, at least for the period of time, the couple of years, since the Van Allen probe launched that particles—ultrarelativistic electrons—can get in so far, they run into something almost like a glass wall, and can’t really get any further. This really was quite an interesting and fascinating puzzle.”

They looked into whether the phenomenon might be related to various actions of the Earth’s magnetic field, or even perhaps a reaction to radio waves broadcast from Earth, but those explanations fell short.

“We were left with the unsatisfying situation that very slow pitch-angle scattering and even slower radial diffusion can conspire to create this sharp gradient in the particle distributions,” Baker said. “To me, that’s not very satisfactory, but it seems to be the explanation.”

“I think its a subject now that our theoretical friends are struggling with and trying to understand and explain,” he added.

Baker says this new information is vitally important for those who may be studying x-rays from the Sun, synchrotron emissions from Jupiter, radio and x-ray emissions from distant nebulae, or extra-gallactic jets.

“All of these are visible because of energetic particles, electrons primarily, moving in strong magnetic fields,” he said. “Examining the details of how the accelerator that is so accessible to us in our own cosmic backyard can really give us much useful information about how acceleration processes work in these more removed systems.”

Baker says it is an exciting time in the field, with a great many instruments and missions collecting data.

“We have quite a golden age, in a sense, of measuring the properties of this entire magnetospheric system,” he said. “When we combine this information that we’re gathering now with the wonderful measurements of the Sun and the driving factors from the Sun, we really have the opportunity to make immense progress and to address the key questions that Van Allen and co-workers uncovered nearly 60 years ago.”

“The results from the Van Allen probes mission have in a real sense been rewriting the textbooks on many aspects of structure, acceleration, transport, and loss,” Baker concluded. “They’re giving us previously undreamt of capabilities.”

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The Super Bowl of astronomy hits Seattle

They’re calling it the Super Bowl of Astronomy, and while we don’t expect cheerleaders shaking their pom-pons or legions of blue-clad number twelves chanting “caw” at a plenary talk about Fermi bubbles or at a poster session about emerging multiwavelength views of planetary nebulae, some 2,600 astronomers, planetary scientists, educators, and journalists will hit the Washington State Convention Center in Seattle for the winter meeting of the American Astronomical Society today through Thursday.

aas_225web_bannerSeattle Astronomy will be on hand, though this is the stargazer’s version of a 415,000-square-foot candy store; with 1,900 scientific presentations crammed into the five days, it’s hard to know where to start! We’ve sketched out a tentative schedule, starting with the welcome address Monday morning and a talk by University of Colorado astronomer Daniel Baker about new discoveries about the Van Allen Belts. We won’t likely call it quits until after a town hall session about the Hubble Space Telescope Thursday afternoon.

A couple of satellite events have sprung up because of the presence of so many astronomy professionals in town. Tuesday evening at Town Hall Seattle the Springer Storytellers will feature five astronomers and their tales of exploration, part of Springer Publishing’s Story Collider project. Wednesday evening at the Museum of Flight NASA astrophysicist Amber Straughn will talk about the James Webb Space Telescope, scheduled to launch in 2018. Friday the Boeing Employees Astronomical Society will hold its holiday banquet, to be keynoted by Robert Nemiroff, founder of the popular website Astronomy Picture of the Day. Follow the links for details about these events.

Information about the AAS meeting is online at the AAS website. If you want to follow on social media, conference participants will be using the hashtag #aas225 with their posts. The AAS is on Twitter at @AAS_Office, and on Facebook as well.

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Comet hunter Machholz to keynote annual Seattle Astronomical Society banquet

Don Machholz

Comet hunter Don Machholz will keynote the Seattle Astronomical Society annual banquet Jan. 24.

The Seattle Astronomical Society always seems to score interesting speakers for its annual banquet, and this year is no exception. Renowned comet hunter Don Machholz will give the keynote talk at the 2015 banquet Saturday, January 24, at the Swedish Club, 1920 Dexter Avenue North in Seattle.

Machholz is a prolific comet finder; he has eleven comet discoveries listed to his credit. The first was Machholz 1978L, discovered in September of that year after more than 1,700 hours of observing. The most recent was comet C 2010 F4 (Machholz). All of his discoveries have been made visually, quite a record in these days of digital cameras, computers, and space telescopes joining in the hunt.

Machholz is also considered to be one of the creators of the Messier marathon, an challenge to astronomers to observe all 110 objects in Charles Messier’s catalog in one night. Machholz has written a guidebook, The Observing Guide to the Messier Marathon: A Handbook and Atlas, published by Cambridge University Press in 2002.

Machholz has written several other books. Decade of Comets chronicles the comets discovered visually between 1975 and 1984. An Observer’s Guide to Comet Hale-Bopp came out in 1996.

It should be a most interesting evening.

Tickets to the banquet have been available for members of the Seattle Astronomical Society for several weeks, and went on sale to the general public today. The cost is $40 for members, and $50 for non-members. But why not sign up? Membership is just $35 annually. The Jan. 24 event will begin with a happy hour at 5 p.m., followed by a buffet dinner at 6 p.m. and the program at 7 p.m.

Further reading:

Don Machholz website

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Spotting black holes

Black holes remain among the more mysterious objects in the universe. Though John Michell and Pierre-Simon LaPlace first posited their existence back in the 18th century, nobody has ever actually seen a black hole. Dr. Sean O’Neill, visiting assistant professor in the Department of Physics at Pacific Lutheran University in Tacoma, attempted to shed some light on these objects that don’t emit any during a talk at this month’s meeting of the Seattle Astronomical Society.

Steve O'Neill

Dr. Steve O’Neill of PLU spoke about black holes at the December meeting of the Seattle Astronomical Society. Photo: Greg Scheiderer.

O’Neill’s talk was titled “If We Can’t See Black Holes, How Do We Know They Exist?” His answer to the question boiled down to the notion that scientists have not yet come up with any other plausible explanation for some of the phenomena that they have seen.

The professor noted that traditional methods of observing astronomical objects simply are not practical for viewing black holes.

It would not work to send a spacecraft for a look. O’Neill pointed out that the nearest likely black hole is some 1,300 light years away from Earth. It would take a craft like Voyager about 25 million years to get there, and then, even if it arrived with its power source and transmitter intact, you would still have to wait 1,300 years to receive any messages about its findings.

“Traveling there is a terrible option,” O’Neill understated. “The direct visit option is bad even for things in the outer solar system, let alone things outside of our solar system.”

Imaging is also well nigh impossible, O’Neill said, and not just because a black hole, by definition, does not emit any light. Black holes, though incredibly massive, are also dense and quite small. Today’s telescopes don’t offer adequate resolution for a visual or photographic look; it would take a scope about ten thousand times the size of Hubble to spot the supermassive black hole at the center of the Milky Way.

Other methods offer some hope. O’Neill says we might well be able to spot the gravitational effects of a black hole, especially one circling another or dancing gravitationally with another massive object. In such cases general relativity predicts gravitational waves in space-time, and these might be observed directly. The approach is to use laser interferometry to detect changes in light wavelength. O’Neill says it’s a complicated process from which it is difficult to separate observational noise.

“In practice, there have been no detections of this phenomenon happening yet, even though most people think it probably does happen,” O’Neill said.

O’Neill says gravitational lensing also holds some promise, especially as observing equipment gets better.

“It’s tough to pick out the individual little black holes, though,” he said, noting that the method is used to look at distant, large, massive objects that lens other distant objects.

Though we haven’t yet seen a black hole, there’s plenty of evidence that infers that they exist. O’Neill shared data from observations of stars orbiting the center of our galaxy, seen in the infrared to cut through the dust blocking our direct visual view. Using Newton’s laws on the data from a number of years to reconstruct the orbits of the stars suggests they’re going around something that is about 3.7 million times more massive than our Sun. Whatever it is, we can’t see it because it doesn’t emit any light of its own.

“It’s tough to come up with a good alternative of what this could be,” O’Neill said. “It’s tough to imagine that gravity just goes wrong at this one point, for some reason, at the center of our galaxy.”

“That’s where we get a lot of direct evidence for what we think is the black hole at the center of our own Milky Way,” he concluded.

Looking at other objects leads to similar conclusions. Cygnus X-1 is a huge source of x-rays that is pulling material from a donor star nearby. The material holds a great deal of potential energy because of the high gravity of the system.

“All of that energy has to be converted into some form,” O’Neill explained. “Some of it is certainly kinetic, because stuff will speed up, but some of it is also going to be thermal energy. It will hit other little particles of gas, all of this will heat up to the point that it starts emitting x-rays, and that’s the stuff that we think we can see.”

One of O’Neill’s research interests is computer modeling of the jets of material often spotted shooting out of the centers of galaxies, such as Centaurus A. He shared a number of these simulations, in which material plummets toward a presumed black hole, doesn’t quite fall in, and then shoots away at great velocity. The models can be rotated to simulate views from various angles and compare the results to actual observations. While it’s an active area of research, O’Neill says most scientists are on the same page with their thinking.

“The reigning theoretical model for these jets by far—there’s essentially no viable alternative—is that fundamentally they’re powered by black hole gravity at the source,” he said.

While O’Neill notes that computer simulations like the ones he creates are way cheaper than observing, he expects that actual observations of gravitational waves from merging black holes are not far off. He also thinks that high-resolution x-ray and radio observations will allow us to see the disks of material around black holes within his lifetime.

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