Author: Andrew

An electrical engineer, amateur astronomer, and diver, living and working on the island of Hawaiʻi.

The Sky Is Falling

Yes… The sky is falling… Literally.

Anyone who spends a good amount of time observing the night sky is well aware of how common meteors are. On any given night you will see five to ten meteors an hour is you observe carefully from a dark site. This rate goes up dramatically during a meteor shower. Most of the meteors you will see are quite small, ranging from dust grains to smallish sand sized bits. Anything large can be quite spectacular. Something the size of a pebble will create a bright meteor, a bright fireball that streaks across the sky.

Bolide Events from 1994 to 2013
The graphic shows atmospheric impact events from 1994 to 2013, credit NASA’s Near Earth Object (NEO) Program
I have personally witnessed many bright fireballs, it is just a function of how much time you spend outside at night. Meteors that are bright enough to light up the landscape, that leave glowing trains of vapor behind, clouds that last for many minutes, that twist and drift in the high atmospheric winds.

Estimates vary widely, but something like 50,000 tons of meteoric material rains down on the Earth every year. The process that allowed our planet to form continues to this day.

Occasionally a larger object enters the atmosphere. Something big enough to reach the ground intact. Or even something big enough to cause damage from the impact. How often this occurs would be a surprise to most of our fellow citizens who pay little attention to the the natural world around them.

The Chelyabinsk event got the world’s attention. A medium sized object exploded in the atmosphere directly over a mid-sized city causing modest damage. Due to the prevalence of camera gear in modern Russia we were treated to an unprecedented view of this event. With historical events like Tunguska, all we have is eyewitness accounts and a few grainy black and white photographs of the damage taken years after the impact. Now we get dozens of videos of the event that detail how it occurred from dozens of viewpoints.

While this event is unusual, it was not unprecedented, objects of this size will continue to impact our planet. Meanwhile the event fades from public awareness, at least until it happens again… Which it will.

To drive home this point researchers at NASA’s Near Earth Object (NEO) Program have released a map of impacts over the last few years. Using atmospheric sensors that detect the pressure wave of the airburst they were able to locate and estimate the size of the larger events. For further details you can read the press release.

The Chelyabinsk meteor can be seen as a large dot over southern Russia. That event may be the largest dot on the map, but it is not alone. It is the number of other dots that may surprise some people. Our planet is impacted regularly.

Mikaelyan Meteor
A meteor breaking up over Groningen, Netherlands, 18:57, 13 Oct 2009, photo by Robert Mikaelyan, used with permission

Astronomers Thrilled by Extreme Storms on Uranus

W. M. Keck Observatory press release…

The normally bland face of Uranus has become increasingly stormy, with enormous cloud systems so bright that for the first time ever, amateur astronomers are able to see details in the planet’s hazy blue-green atmosphere.

“The weather on Uranus is incredibly active,” said Imke de Pater, professor and chair of astronomy at the University of California, Berkeley, and leader of the team that first noticed the activity when observing the planet with adaptive optics on the W. M. Keck Observatory in Hawaii.

Uranus NIRC2
Infrared images of Uranus (1.6 and 2.2 microns) obtained on Aug. 6, 2014, with adaptive optics on the 10-meter Keck II telescope. Credit: Imke De Pater (UC Berkeley) & W. M. Keck Observatory
“This type of activity would have been expected in 2007, when Uranus’s once every 42-year equinox occurred and the sun shined directly on the equator,” noted co-investigator Heidi Hammel of the Association of Universities for Research in Astronomy. “But we predicted that such activity would have died down by now. Why we see these incredible storms now is beyond anybody’s guess.”

In all, de Pater, Hammel and their team detected eight large storms on Uranus’s northern hemisphere when observing the planet with the Keck Observatory on August 5 and 6. One was the brightest storm ever seen on Uranus at 2.2 microns, a wavelength that senses clouds just below the tropopause, where the pressure ranges from about 300 to 500 mbar, or half the pressure at Earth’s surface. The storm accounted for 30 percent of all light reflected by the rest of the planet at this wavelength.

When amateur astronomers heard about the activity, they turned their telescopes on the planet and were amazed to see a bright blotch on the surface of a normally boring blue dot.

‘I got it!’

French amateur astronomer Marc Delcroix processed the amateur images and confirmed the discovery of a bright spot on an image by French amateur Régis De-Bénedictis, then in others taken by fellow amateurs in September and October. He had his own chance on Oct. 3 and 4 to photograph it with the Pic du Midi one-meter telescope, where on the second night, “I caught the feature when it was transiting, and I thought, ‘Yes, I got it!’” said Delcroix.

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Leonid Meteor Shower

The Leonids are one of the better known annual meteor showers. Some years see high Leonid activity, with amazing numbers of meteors. This shower has occasionally created true meteor storms. Unfortunately 2014 is not predicted to be one of those years, with very modest numbers expected.

Leonids in Orion
A pair of Leonid meteors streak through Orion
The shower will peak on November 17 around 22:00UT, with an expected ZHR of around 15 meteors per hour. While this occurs in the middle of the day for the islands, the Leonids exhibit a broad peak allowing viewing for days before and after maximum. Moonlight should not be a problem with a thin waning crescent in the sky.

Due to the gravitational influence of Jupiter, the Leonids are not expected to produce any exceptional showers for some decades. We are unlikely to see any repeats of the early 21st century storms anytime soon.

All Pau

Living in Hawaiʻi you pick up a few additions to your vocabulary. For centuries the islands have been a stew of languages, each borrowing words from one another. Hawaiian, Portuguese, Chinese, Japanese, English, Spanish and more have all added to the flavor of these islands. Everyone uses a few words from other languages in everyday conversation. Then there are local folks who grew up speaking the full mixture, a pidgin unique to the islands.

Radio
A handheld radio used at Keck for daily communication.
Working with a bunch of island guys you need to learn a bit of pidgin simply to understand the conversations around you. To an English speaker, such as myself, the syntax seems mixed about. The words are mostly English and Hawaiian, with a clear context and a little exposure you begin to pick it up. After a while it seems natural to hear pidgin around you.

Some of the words that Hawaiian supplies seem much better than the English equivalents, it is understandable that they are used in preference to the English words. Some are simply more appropriate on an island… Mauka and Makai make perfect sense where everything is either towards the mountain or towards the sea. Puʻu us the perfect name for the numerous volcanic hills that dot the island. Puka, for small hole, just sounds right.

My favorite is Pau, meaning finished or done, a word that is commonly heard on the Keck radio channels. “How are you guys doing up there?” might go the radio chatter, “We all pau!” Something about the word just works, the sound and the meaning in agreement.

I expect these words will stay in my vocabulary, alongside British expressions I picked up living in England decades ago. Language is a fluid and dynamic thing, part of the richness of our lives.

Unintended Photos

Sometimes the photo does not quite work as planned. Turn to shoot the guys following me into a cave, except that the flash does not fire… It helps to turn it on. Expecting the result to be a discard, I am surprised to see a rather interesting photo…

Entering the Cave
Divers entering a cave, accidental long exposure as the flash did not fire.

Mysterious G2 Cloud Near Black Hole Identified

W. M. Keck Observatory press release…

The mystery about a thin, bizarre object in the center of the Milky Way headed toward our galaxy’s enormous black hole has been solved by UCLA astronomers using the W. M. Keck Observatory, home of the two largest telescopes on Earth. The scientists studied the object, known as G2, during its closest approach to the black hole this summer, and found the black hole did not dine on it. The research is published today in the journal Astrophysical Journal Letters.

G2 at the galatic center
An image from W. M. Keck Observatory near infrared data shows that G2 survived its closest approach to the black hole. Credit Andrea Ghez/Gunther Witzel/UCLA Galactic Center Group/W. M. Keck Observatory
While some scientists believed the object was a cloud of hydrogen gas that would be torn apart in a fiery show, Ghez and her team proved it was much more interesting.

“G2 survived and continues happily on its orbit; a gas cloud would not do that,” said Andrea Ghez, UCLA professor of physics and astronomy who holds the Lauren B. Leichtman and Arthur E. Levine Chair in Astrophysics, and directs the UCLA Galactic Center Group. “G2 was completely unaffected by the black hole; no fireworks.”

Instead, the team has demonstrated it is a pair of binary stars that had been orbiting the black hole in tandem and merged together into an extremely large star, cloaked in gas and dust, and choreographed by the black hole’s powerful gravitational field.

“G2 is not alone,” said Ghez, who uses Keck Observatory to study thousands of stars in the neighborhood of the supermassive black hole. “We’re seeing a new class of stars near the black hole, and as a consequence of the black hole.”

Ghez and her colleagues — who include lead author Gunther Witzel, a UCLA postdoctoral scholar in Ghez’s research group, and Mark Morris, a UCLA professor of physics and astronomy — studied the event with both of the 10-meter telescopes at Keck Observatory.

Continue reading “Mysterious G2 Cloud Near Black Hole Identified”