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Wind topples California’s famous Tunnel Tree

January 9, 2017 Leave a comment
pioneers-cabin-tree-circa-1966
This photo of California’s Pioneer’s Cabin Tree, dated 1866, is from the Library of Congress.

The Pioneer Cabin Tree, a California landmark loved by tourists for decades, has been toppled by wind.

A giant sequoia, the huge tree was 150 feet tall. The cutout in its trunk was wide enough to drive cars through and, over the years, many cars did pass under the tree.

Eventually California authorities closed access to cars, but in recent years there has been a hiking trail that leads to it and visitors could still stand in the cutout.

tunnel-tree-photo-by-claudia-beymer
This photo of the base of California’s Tunnel Tree was posted on the Facebook page of the Calaveras Big Trees Association. Image by Claudia Beymer.

Located in Calaveras Big Trees State Park, the Pioneer Cabin Tree – also known as the Tunnel Tree – was estimated to be over 1,000 years old. The large hole in its trunk was carved by owners of the land on which it grew in 1880.

A report in the San Francisco Chronicle explained that there is no way to be sure of the reason why the Tunnel Tree could not withstand the storm that has hit the Golden State in recent days. That storm, the worst in at least a decade, flooded Calaveras Big Trees State Park. The Chronicle explained that the Tunnel Tree’s shallow root system, typical for a sequoia, was likely a factor.

fallen-tunnel-tree
This photo shows the splintered remains of California’s Tunnel Tree on Jan. 8, 2017. Image courtesy Calaveras Big Trees Association, photo by Jim Allday.

Giant sequoias (Sequoiadendron giganteum), also known as redwoods, are the world’s largest organisms by volume. They can grow to a height of 85 meters and have been known to live for more than 3,500 years.

Now that the Pioneer Cabin Tree has fallen, there are no longer any known living sequoia trees with tunnels through their trunks.

Spacecraft in solar orbit regains contact with Earth

August 24, 2016 Leave a comment
STEREO image of whole sun, Feb. 2, 2011 - courtesy NASA

This image shows our sun’s far side. It was obtained by the STEREO probes on Feb. 2, 2011 at 23:56 UT. Image courtesy NASA.

A probe launched by NASA in 2006 has resumed communication with the agency after nearly 23 months of silence.

The STEREO-B spacecraft, which orbits the sun, lost contact with Earth on Oct. 1, 2014.

The Deep Space Network reestablished the link with STEREO-B at 6:21 pm EDT on Sunday.

The long interruption in communication with the spacecraft was most likely the result of a series of events that began with a test of its command loss timer. The device is a kind of automated switch that allows the spacecraft to recover after a hardware failure. It functions by re-setting the hardware if no commands are received for a certain period of time. In STEREO-B’s case, that re-set time was three days.

NASA explained a likely scenario for the communications failure at a website posted shortly after the loss of contact event and still available here. An animated film that provides one possible model for the probe’s communication failure is also available.

STEREO-B’s navigation system probably failed because it was unable to detect guide stars. This caused the probe’s high gain antenna to be pointed away from Earth, which meant that it could not receive a signal.  The breakdown in the star tracking system was likely the result of a failed laser.

“Basically, we made a mistake in not accounting for one of those individual lasers failing,” Dr. Joseph Gurman, the STEREO project scientist at NASA’s Goddard Space Flight Center, said. “The data still looked good coming out of the unit as a whole even though one laser was bad. That got us into a situation where the spacecraft was getting bad navigational information.”

STEREO-B remains in an uncontrolled spin, a problem for which there is not currently enough power available to correct. The spacecraft obtains energy by means of solar arrays that extend out from its main section.

Gurman explained that NASA scientists are not sure how much power the probe’s batteries can produce or whether they can be fully re-charged.

“We don’t know if the batteries are damaged,” he said. “We know they can take some charge.”

Whether the spacecraft’s instrumentation is still functional is also unknown.

“I would say that we know nothing about the state of the instruments at this point,” Gurman said.

NASA will proceed cautiously to investigate the STEREO-B probe’s status. What Gurman and his colleagues want to avoid is any command that would return STEREO-B to an uncontrolled spin.

“We have an inertial problem that is giving bad information to the control system on the spacecraft,” he said. “We have to proceed in a step-by-step method.”

The first step will be to figure out the extent to which the probe has, to put it metaphorically, any gas in its tank.

“We have to heat up the probably frozen fuel in the fuel tank,” Gurman explained. “We can proceed from there to use the thrusters to right our attitude by using the autonomy software.”

Gurman is optimistic, though, about the prospects for obtaining more data about the sun from STEREO-B. NASA’s prior experience with another spacecraft that experienced a communication failure – the Solar and Heliospheric Observatory – indicates that instruments can survive with little or no damage, even in the cold of space, for quite some time.

“On SOHO, there were 12 principal investigator experiments,” Gurman said. “Only one mechanism in one telescope was damaged in such a way that we really couldn’t use the instrument. There was one instrument that suffered some degradation. That’s about it. We’re cautiously optimistic that we’ll be able to regain most of the scientific capability, if not all, that we had before.”

In any case, the STEREO mission formally ended eight years ago, so any data obtained from STEREO-B is beyond what was expected at the time of launch.

“Anything we get is gravy, to say the least,” Gurman said.

The probe’s twin, STEREO-A, also revolves around our closest star.

STEREO is an acronym that shortens the twin probes’ formal name – Solar Terrestrial Relations Observatories.

 

Comet ISON reaches perihelion

November 28, 2013 Leave a comment

An ancient comet that has been moving through the solar system since discovery last year reached perihelion Thursday and observers are speculating that the sun’s heat is breaking it up.

Comet ISON arrived at the point in its orbit closest to the sun at 18:25 UT Thursday (11:25 am MST).

At perihelion the comet is about 730,000 miles from our star. It has brightened considerably as it approached the sun, reaching a magnitude similar to the full moon.

Emily Lakdawalla and Bruce Betts of the Planetary Society are blogging about the event here.

You can see images obtained by NASA’s Solar Dynamics Observatory here.

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Tonight is International Observe the Moon Night

October 12, 2013 Leave a comment

It’s always fun to look up at Earth’s closest neighbor and indulge some curiosity about the Moon, but tonight’s a special night to do it: it’s International Observe the Moon Night.

The celebration, sponsored by an array of scientific and educational organizations along with some dedicated Moon enthusiasts, has prompted a wide variety of events all over the world. You can find one near your home if you visit this webpage.

If you’re looking for your own activities, obviously a good place to start is by going outside and observing Luna. You don’t even need a telescope. If the night sky is clear, the naked eye will allow you a good view of lunar maria, or “seas,” and the Moon’s highlands.

If you use binoculars, attach them to a stand or tripod if you have one.

The Moon is at first quarter phase tonight, so it is not likely that an observer will be able to see the phenomenon known as Earthshine, in which the night side of the moon is visible when sunlight reflects off the surface of Earth. Earthshine is visible only when the Moon is at or near new moon phase.

After you’ve looked at the Moon, it might be fun to try your hand at this Mission Moon activity. Participants work in teams to figure out the best place on Luna for a base. The activity is suitable for kids from about third grade and up. You can also try the Moon Mappers activity.

Before going outside to have a look at our closest celestial neighbor, you might enjoy watching this NASA video about how the Moon formed and its history.

Labeled moon map - courtesy WikimediaLabeled Moon map courtesy Wikimedia.

Note: This story also appears at Examiner.com.

Uranus is visible in night sky

October 9, 2013 Leave a comment

The solar system’s seventh planet, Uranus, recently was at opposition from Earth and is currently visible with binoculars if you know where to look in the night sky.

You’ll want to look near the border of the constellations Pisces and Cetus. This Universe Today report should help.

The best time to observe is around midnight local time.

Uranus - courtesy Wikimedia

This image of Uranus was obtained by the Voyager 2 spacecraft in 1986.  The blue-green color is the result of the presence of methane in the planet’s atmosphere.  Courtesy Wikimedia.

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Nobel prize for physics goes to Higgs boson scientists

October 8, 2013 Leave a comment

The Nobel prize in physics has been awarded to the scientists who predicted the existence of the  Higgs boson nearly 40 years ago.

Francois Englert and Peter Higgs were granted the coveted award this morning by the Royal Swedish Academy of Sciences.

They separately proposed, way back in 1964, that a particle we now know as the Higgs boson allows matter to acquire mass. The existence of that particle was confirmed in 2012 by scientists working at the CERN laboratory in Switzerland.

 

Draconid meteor shower continues tonight

October 8, 2013 Leave a comment

The Draconid meteor shower will again be visible tonight in the northern hemisphere.

The meteor shower occurs when dust from Comet Giacobini-Zinner enters Earth’s atmosphere and ionizes, creating a “shooting star” look.

The meteors appear to come out of the constellation Draco (the dragon) and the flurry of them will appear highest in the sky shortly after sunset. As night advances the spectacle drops below the horizon.

The Draconids can be unpredictable in their intensity. Astronomers have not predicted a noteworthy display from the Draconids this year, but in some years the number of meteors is impressive. In 2011 more than 600 per hour were visible.

The reason for 2011’s display was that Comet Giacobini-Zimmer was at the perihelion of its orbit around the sun.

Earth’s moon is not likely to be much of an impediment to viewing the meteors, as it is in waxing crescent phase now.

Observers will have the best opportunity to see meteors if they choose a viewing location far from city lights.

Graphic courtesy EarthSky.org.

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