The "Ice Giant" Neptune. Credit: NASA/Voyager 2

Would you believe we discovered the planet Neptune only one year ago? Weird; I seem to have heard about this planet all my life—it was even my favorite planet at one point, back in childhood. What's this paradox?

Well, not a paradox—just semantics. It has been one year since Neptune's discovery. One Neptunian year. It takes Neptune, the most distant known (official) planet, about 165 years to orbit the Sun one time.

Doing the math backward, 2011 – 165 = 1846. Neptune was officially discovered on September 23rd of that year in a sort of virtual team effort-slash-international-rivalry extravaganza by at least three people. (To be nit-picky, it was actually July 12th when Neptune completed one Neptunian year since its discovery, since the Neptunian year is a couple of months short of exactly 165 Earth years….)

Usually, the discovery of a celestial object is credited to one individual: the first to spot it through a telescope. Sometimes there is battle over the credit because two people may have spotted the object around the same time, and documented proof of who found it first is needed to settle the debate, or lack thereof to let the controversy go on.

But Neptune was the first planet to be discovered mathematically, based on observed perturbations in the motion of Uranus (Uranus, incidentally, was the first planet to actually be discovered; it's difficult to say that any of the other planets were "discovered" in the conventional sense, as all of them—Mercury, Venus, Mars, Jupiter, and Saturn—are naked-eye objects, and so have been available to human eyesight since human eyesight was invented).

In Neptune's case, in France and in England, Alexis Bouvard and John Couch Adams, respectively, each deduced that Uranus' orbital perturbation was caused by the influence of another as yet undiscovered planet. Another Frenchman, Urbain Le Verrier, mathematically predicted the position of this unseen lurker, and German astronomer Johann Galle turned a telescope to the predicted position, finding Neptune less than a degree away. Eventually, credit for Neptune's discovery—or at least the process of discovery–was divvied up among the group.

Why was Neptune once my favorite planet in childhood? Well…because it's blue, of course! Just as good a reason as any, and blue was my favorite color. Like its slightly larger near-twin, Uranus, Neptune's upper atmosphere is made mostly of hydrogen and helium gas, but the presence of methane tints it blue. The thick atmospheric shell is believed to extend downward 10 to 20 percent the distance to the planet's center.

Deeper down is thought to exist a mantle containing significant amounts of volatile materials, like methane, ammonia, and water. This hot, dense, high-pressure fluid shell might be thought of as an "ocean" more than an atmosphere—although the distinction between gas and liquid is blurred by the extraordinary temperature and pressure of the material (taking an extreme example of what I mean, even the Sun's core, with a density a hundred times greater than liquid water on Earth, is considered a gas–or plasma–by virtue of its great temperature).

Nevertheless, sometimes Neptune, and Uranus, are referred to as "liquid giants"—or even "ice giants", though it's difficult for me to reconcile the term "ice" with the multi-thousand degree temperatures deep down inside these worlds….

Under all that stuff, Neptune's solid core, made of rock and nickel iron primarily, has a mass not much greater than planet Earth—as if, at the center of this giant piece of liquid confection, there exists a crunchy center, a shrouded planet Earth. What a gem! And maybe literally, as it is speculated that deep inside the planet's mantle, carbon atoms coming from methane may be squeezed by the pressure into diamond crystals, which "rain" down upon the rocky core. Neptune, planet of riches…if only….

At Chabot, we'll be having a Neptune's First Anniversary since Discovery celebration on that date, September 23rd. Hope you can join us!

Counting craters on a Lunar Reconnaissance Orbiter image
of the Moon's surface. NASA/LRO

Ever been out on a clear, lazy night and tried to count the stars–or the kind that fall from the sky during a meteor shower? How about craters on the Moon, or distant galaxies in deep space?

If you like this kind of work, there is a job for you! Several, in fact….

In this day of the Internet and electronic databases, our ability to store, process, share, and, yes, be overwhelmed by information is greater than ever before. In fact, our ability to analyze data is only outmatched by our capacity to acquire it—which offers some pleasing challenges: buried in the riches of data of our Universe that we are piling up around us, there is plenty of opportunity for just about anyone to grab a shovel and dig in, sharing in the adventure of exploration of the Universe around us!

Okay, that was the sales pitch, here are some details.

Count some stars! Subject: stars visible to the naked eye; what's being investigated: the impact of urban light pollution on our access to the simple wonders of the night sky. Every year, Windows to the Universe conducts the Great Worldwide Star Count citizen science project, enabling anyone who can look up at the night sky and count some of the stars there to participate in real science. We're already into the Count, which runs this year from October 31st through November 12th. For details on how to participate, check out their website.

Results from the Great Worldwide Star Count are presented in a global map showing the "limiting magnitude" from thousands of locations where citizen scientists observed. The limiting magnitude is a measure of brightness of the faintest star that can be seen from a given location.

How about craters on the Moon? Looking at the Moon through a small telescope, you can count some of the largest craters—those that are typically at least a mile or so across. By virtue of the powerful LROC camera on NASA's Lunar Reconnaissance Orbiter (LRO), the surface of the Moon is rabidly being photographed to a level of detail that reveals craters as small as a foot and a half across!

Craters are a fantastically rich source of information regarding the history of our solar system, each one a record of a single meteoroid impact which, when examined in context with all the rest, allows scientists to forensically piece together the puzzle of the formation of the Moon and our region of the solar system.

While there are estimated to be at least 300,000 lunar craters with diameters of about half a mile or greater on the side of the Moon facing the Earth, smaller craters are estimated into the millions, and microcraters are most likely uncountably common.

This means science needs your help! And you can give it, at Moon Zoo. Log onto the Moon Zoo website, register yourself as an official lunar explorer, and have at it, friend. Examining LRO images of the Moon's surface, you will count and classify craters and boulders, and mark unusual and interesting lunar features, as you explore. There are so many images that have been acquired by LRO that in many cases you will be the first person ever to lay eyes on the particular patches of the Moon you examine—you might even run across something remarkable, like a derelict lunar robot from the 1960s (it's happened!). Best of all, your work will count, your data feeding into a growing database from Moon Zoo explorers all over the world.

A sibling site to Moon Zoo—Galaxy Zoo—lets you examine and classify galaxies imaged by the Hubble Space Telescope. And since there are millions upon millions of unclassified galaxies that have been caught in Hubble's telescopic net, you'll be covering unexplored territories of space and contributing to our planet's understanding of the Universe….

There's a lot of work to do out there, and the glittering treasure trove of data just keeps getting larger and larger—so get to work!

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The Thirty Meter Telescope would be built in Hawaii, atop Mauna Kea at around 13,000 feet. Artist's interpretation courtesy of TMT Observatory Corporation.

Originally reported for KQEDnews.org.

Scientists from the University of California are working with a team of international researchers on one of the most high-profile science projects of this decade: an effort to construct the largest optical telescope on Earth.

The $986 million project is planned for the summit of Mauna Kea, on Hawaii’s Big Island, and will feature a primary mirror 98-feet in diameter.

Scientists working on the project hope to begin construction next year and complete it by 2018 or 2019. They say the facility, dubbed the Thirty Meter Telescope, will allow astronomers to observe with much more clarity some of the earliest stars and galaxies of the universe and investigate what they’re made of.

“We’ll be able to look back at the baby pictures of the universe and trace how it developed,” said Michael Bolte, director of the University of California Observatories and a member of the board of directors for the new telescope.

The telescope won approval last month from the University of Hawaii Board of Regents, which holds the lease to the site.

In addition to exploring the farthest reaches of the universe, the telescope also will be able to routinely and easily produce images of the more than 450 planets that have been discovered orbiting stars outside of our solar system.

Today, the existence of these so-called “exoplanets” can only be inferred by measuring the gravitational tugging forces exerted by the stars they orbit. The telescope also could help determine if some of them have atmospheres similar to Earth’s – the precursor to finding life on another planet.

“It will be one of the most important scientific facilities of the 21st century,” said Bolte, who is also a professor of astronomy at UC-Santa Cruz. “When we look back, it’s going to be the Large Hadron Collider and the Thirty Meter Telescope and I’m not sure what else.”

The project is a joint effort of the University of California, the California Institute of Technology and the Association of Canadian Universities for Research in Astronomy.

A sizable amount of its funding is coming from the Bay Area. The Betty and Gordon Moore Foundation, in Palo Alto, has pledged $200 million toward the telescope’s construction. The University of California and Caltech each plan to raise $50 million. And contributions are expected from the Canadian universities, as well as the governments of China, India and Japan. But 10 to 20 percent of the telescope’s budget still remains to be raised, said Bolte.

The new telescope’s 98-foot (30 meter) mirror would be three times as big as the mirrors on the twin Keck telescopes in Hawaii, currently the biggest in the world, and also owned by the University of California and Caltech. The telescope would produce images three times as sharp as the 33-foot Keck telescopes on Mauna Kea, and would be able to look at objects that are nine times fainter. This would make it possible for scientists to better understand the origins of the universe.

“The universe is 13.7 billion years old and we can see objects that are 13 billion years away, but all we get is fuzzy blobs,” said UC-Santa Cruz astronomer Garth Illingworth, chair of the telescope’s Science Advisory Committee. “We’d like to learn more about these stars and galaxies.”

In January of 2010, Illingworth and his team announced that they had observed the most distant galaxies ever seen. Looking back in time 13 billion years, they found galaxies that were just 600 or 700 million years from the Big Bang. Photographs of these galaxies, which appear as several tiny dots, were made by the Hubble Space Telescope.

Space-based telescopes like Hubble have an advantage over ground telescopes because they don’t have to contend with the blurring caused by the Earth’s atmosphere. But they’re more expensive and therefore, smaller. Hubble’s mirror is less than 8 feet in diameter.

Bigger ground-based telescopes can gather more light than small space-based telescopes. So they make objects that once were faint appear brighter. And the additional light gives researchers information on the chemical composition of objects like stars.

When astronomers understand what a star is made out of, they can better establish its age. And this allows them to plot out the history of the universe more accurately. What’s understood now is that the Big Bang was followed by a period of darkness that astronomers call the Dark Ages. But it’s not clear how long that period lasted.

“There’s controversy about the period before which there were no stars,” said Jerry Nelson, UC-Santa Cruz astronomer and project scientist for the telescope. “The idea is to establish bounds on this. The question is when do you get stars forming that burn holes through this opaque stuff?”

In addition to answering questions about the history of the universe, observers say the telescope could also eventually lead to new energy sources based on the nuclear fusion that fuels stars.

“All those points of light are nuclear furnaces,” said bestselling San Francisco author Timothy Ferris, who wrote “Seeing in the Dark” and other books about astronomy and telescopes. “And they have something to teach us.”

The telescope’s mirror will be made out of 492 closely fit individual hexagonal glass mirrors. The Keck telescopes were the first to use these segmented mirrors to get around the problems created by gigantic individual mirrors. The Keck telescopes were so successful, said Illingworth, that UC and Caltech envisioned the Thirty Meter Telescope as a way to scale-up the Keck model.

TMT Fly-Through from Thirty Meter Telescope on Vimeo.

But big ground-based telescopes have their limitations. Though they can give astronomers more light to study, they can’t by virtue of their size alone make objects appear sharper. To reduce the blurring caused by the atmosphere, scientists use a series of techniques called adaptive optics.

“Adaptive optics is like putting glasses on a big telescope,” said Nelson. A telescope with adaptive optics not only sees sharper images of stars, it also sees more stars.

An expensive and technically complicated process, adaptive optics was used on telescopes for the first time to correct distortions on the Keck telescopes. The technique takes advantage of a layer of the atmosphere that starts about 50 miles above the Earth. This layer is made up of sodium atoms brought in by small meteorites that vaporize as they enter the atmosphere.

Scientists point an orange laser toward the sodium layer. The laser excites the sodium atoms, which become like artificial stars, radiating light back toward the telescope. The process allows researchers to correct for atmospheric turbulence, which causes phenomena such as the twinkle that we see around stars.

Other telescopes in the range of the Thirty Meter Telescope are in the works. An 80-foot mirror called the Giant Magellan Telescope is being spearheaded by a group that includes the Carnegie Institution for Science in Pasadena, Harvard University, the universities of Texas and Arizona and the government of Korea. That telescope is scheduled to be completed in 2018. And Europe is working on the aptly named Extremely Large Telescope, which would have a 138-foot mirror.

“They’re strongly complimentary,” said Bolte. “The Giant Magellan and the European telescope will be in the southern hemisphere, in Chile. So we’ll have access to the entire sky.” Having several of these instruments, he said, would make valuable telescope time more readily available to astronomers.

The Thirty Meter Telescope, which would be built at an elevation of about 13,000 feet, has not been without controversy. Environmentalists say its construction would harm the wekiu bug, a native species that lives atop high Hawaiian peaks. Some Native Hawaiians have come out in opposition, saying that the summit of Mauna Kea is sacred and should not have any more construction.

Scientists hope that the Thirty Meter Telescope will provide answers for many current astronomy questions: What is the invisible matter that makes up 25 percent of universe? What is the mysterious energy that is making it expand faster and faster? But Bolte suspects that just as telescopes in the past surprised scientists by revealing that the planets orbit the Sun and that the universe is expanding, the new telescope’s contributions are impossible to fully predict.

“Every time you build a new telescope with significant new capabilities, you usually solve the problems of the day and find new things you didn’t even know were there,” Bolte said. “The Thirty Meter Telescope will be a bigger jump than any other jump we’ve had, so the new discoveries will be all the more unexpected.”

***

TMT Overview from Thirty Meter Telescope on Vimeo.

Check out these QUEST TV and Radio stories about other University of California astronomy projects:

Illuminating the Northern Lights

Exoplanets

SETI: The New Search for ET

The Planet Hunters

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The Hubble Space Telescope being serviced by Space Shuttle
Atlantis astronauts in May 2009. Credit: NASA

Galileo's telescope had a magnification of only about 27x, allowing him to see that Venus has phases like the Moon, Jupiter has four large moons of its own, Saturn does not appear as a simple disk but has unusual "projections" to either side, and the Milky Way contains far more stars than is apparent to the naked eye. And though these are features that can be seen through the least powerful home telescopes today, Galileo's observations changed the way we look at the universe.

Hubble has done the same thing, but on a modern scale of magnitude. Not a large telescope by the standards of ground-based behemoths like Keck in Hawaii (Hubble's primary mirror is 2.4 meters in diameter), Hubble's "edge" is it's location in space, orbiting the Earth over 300 miles high, outside of our atmosphere. Particularly in its earlier days before ground based telescopes were using adaptive optics techniques to compensate for atmospheric distortion, Hubble's vision on the universe was unparalleled in its clarity.

Here's is a recap of a few of the many big discoveries Hubble has made possible:

Dark Energy: By accurately measuring the distance and velocity of distant supernovae, over a large range of distances, Hubble has refined out knowledge of the rate of expansion of the universe–leading to the discovery that the expansion of the universe is actually accelerating, contrary to what was expected. Scientists suggest the existence of a mysterious "dark energy" throughout the universe that exerts an antigravitational repulsive pressure on the cosmos.

Age of the Universe: Since Edwin Hubble (for whom the Space Telescope was named) discovered that the universe is expanding, astronomers have been trying to determine how long ago the expansion began–how long ago the "starting gun" of the Big Bang was fired, and thus the beginning of the universe. Through precise observations with the Hubble, astronomers in recent years have been able to peg it between 12 and 14 billion years. (Most recently, observations made with the WMAP mission have honed that down to 13.7 billion years, give or take 0.13 billion.)

Supermassive Blackholes: Hubble found the clues that point to the existence of "supermassive" blackholes at the heart of maybe most–or every–galaxy. The Milky Way's own central blackhole has a mass equivalent to four million Suns.

Stellar Dust Disks: Before the first extrasolar planets were actually detected, Hubble observations revealed that flat disks of dust encircling young and developing star systems–aka "protoplanetary disks"–is commonplace. This has given us a glimpse at what our own solar system may have looked like before the planets formed.

It has been seven years since the last Hubble servicing mission, with another servicing scheduled a few years ago cancelled in the wake of the Columbia disaster. Several failing systems will be repaired or replaced this time, and other instruments are receiving upgrades that will make Hubble more powerful than ever in its declining years.

This mission to service the Hubble will be the last. Since NASA is retiring the Space Shuttle fleet after 2010, we will no longer have a space vehicle large enough to carry upgrade and replacement equipment to and from the Hubble. After that, the next new big space-based descendent of Galileo's spyglass will be the James Webb. Stay tuned…

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The project was headed by a group at a university in Toronto and a group at a university in Paris. Canada and France sponsor the 4-meter telescope that is used to discover and observe the supernovae from the point of explosion to the final days when the supernova fades from view. We call this the imaging part of the program. This data constrains the apparent brightness and life cycle of the supernova, and eventually the absolute distance to the supernova.

Our contribution to the project was primarily through our affiliation with Keck Observatory. We were typically awarded four nights a year to observe recently discovered supernovae spectroscopically. The data is used to determine the redshift and the kind of supernova explosion.

The supernovae are used to study the rate of expansion of the universe. It was this type of experiment that was first used to discover that the universe is actually dominated by dark energy.

No one really suspected the presence of dark energy for almost the entirety of the 20^th century. Now, we not only know it exists but are actually trying to understand it in the same way we understand gravity, protons, and electrons. That is where projects like the Supernova Legacy Survey come in. With projects like this, we work to collect enormous samples of well-studied supernovae that can improve our understanding of dark energy.

We use a certain type of supernova as yardsticks to measure distances in the universe. We then model the affects of dark energy on the expansion history of the universe by comparing distances and rates of expansion. This comparison is typically represented in a Hubble Diagram.

The Supernova Legacy Survey has been very successful in its attempts thus far. On the right, I show the Hubble Diagram from the first year of data. This is less than 20% of the full sample. The dotted line outlines the expectations of the 1990's cosmology crowd. The solid line shows the prediction from the more sophisticated cosmologists of the 21^st century. As you can see, the original expectations were pretty far off the mark – the supernovae just don't lie on top of the dotted line.

Now that this program is finishing up, we should be seeing similar figures that are teeming with supernovae. Future programs should do an even better job of making these measurements. Someday we may actually understand this dark energy thing, it may turn out to be something else completely new and unexpected!

Kyle S. Dawson is engaged in post-doctorate studies of distant supernovae and development of a proposed space-based telescope at Lawrence Berkeley National Laboratory.

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Venus Landing. Credit:
Soviet Planetary Exploration ProgramIt's time to get back to some of the reader’s questions. Over the last couple of months I've focused on the easy ones like "how big is the universe?". Now, people are asking the tough ones, like that from Mike:

"There’s been a recent debate in our local papers regarding Venus' high planetary temperature being related to the dearth of carbon dioxide on the planet. Apparently Venus is much, much hotter than Mercury, even though Venus is twice as far from the sun. Could you explain a bit about our system’s planets and how they differ compositionally? What is it about the Earth's composition of elements that makes it just right for 99% of the life on the planet? I say 99% because it seems 1% of the life is strange enough to exist in all sorts of harsh conditions."

When it comes to the landscape of our own neighborhood, it gets a little more complicated for me. I have a tendency to look right past the solar system in my research of the distant Universe. I'm sure there's an explanation for this in the cliché of missing the forest for the trees. I just do it in reverse.

The Trees

Hubble Deep Field. Credit:
R. Williams, The HDF Team (STScI), NASATruth is, the trees are quite intriguing in their own right. I think people are more impressed with the observations of our solar system because the proximity lends to very detailed images and observations. Compare an image of the surface of Venus to one of the deepest images from Hubble Space Telescope. The image of Venus fits within our sense of scale that we established in our time here on Earth. You can even see familiar rocks and the feet of the Soviet robot. The Hubble Deep Field… needs a bit of explanation.

For the rest of the year, I am going to pull back from the farthest reaches of the universe and focus on Venus and the other planets. It will give me a chance to learn a little about what the Solar System actually looks like. It will also give me a chance to explore some of the most breath-taking images that NASA has created. I'm just going to have to do a little research to get it right.

Kyle S. Dawson is engaged in post-doctorate studies of distant supernovae and development of a proposed space-based telescope at Lawrence Berkeley National Laboratory.

latitude: 37.6797, longitude: -121.698