Sometimes I complain about the earthly weather, but mostly I like to post about astronomy and space events. Hope you enjoy the articles.
By: Susie77, 9:40 PM GMT on April 28, 2009
Have any of you guys ever tried growing tomatoes in those topsy-turvy things they advertise? If so, how did that work out? Is it really better? Is it true that you have to water them every single day? I'd appreciate any hints if you have 'em.... have been thinking of trying that out.
By: Susie77, 12:22 AM GMT on April 26, 2009
Space Weather News for April 25, 2009
SUNSET CONJUNCTION: When the sun goes down on Sunday, April 26th, step outside and look west. An exquisitely-slender crescent Moon is lining up with Mercury and the Pleiades star cluster for a three-way conjunction in the sunset sky. Click here for the full story and a sky map: http://spaceweather.com/headlines/y2009/24apr_eveningsky.php
UNEXPECTED SOLAR ACTIVITY: The sun produced an unexpected burst of activity on April 23rd when an enormous prominence rose over the northeastern limb and erupted. A coronal mass ejection (CME) billowed away from the blast site, but the billion-ton cloud is not heading toward Earth. Visit http://spaceweather.com for movies of the event.
By: Susie77, 2:04 AM GMT on April 18, 2009
Venus Disappears during Meteor Shower
April 17, 2009: Picture this: It's 4:30 in the morning. You're up and out before the sun. Steam rises from your coffee cup, floating up to the sky where a silent meteor streaks through a crowd of stars. A few minutes later it happens again, and again. A meteor shower is underway.
One of the streaks leads to the eastern horizon. There, just above the tree line, Venus and the crescent Moon hover side by side, so close together they almost seem to touch. Suddenly, Venus wavers, winks, and disappears.
All of this is about to happen--for real.
On Wednesday morning, April 22nd, Earth will pass through a stream of comet dust, giving rise to the annual Lyrid meteor shower. At the same time, the crescent Moon and Venus will converge for a close encounter in the eastern sky. Viewed from some parts of the world, the Moon will pass directly in front of Venus, causing Venus to vanish.
The source of the meteor shower is Comet Thatcher. Every year in late April, Earth passes through the comet's trail of debris. Flakes of comet dust, most no bigger than grains of sand, strike Earth's atmosphere traveling 110,000 mph and disintegrate as fast streaks of light. A typical Lyrid shower produces 10 to 20 meteors per hour over the northern hemisphere, not an intense display. Occasionally, however, Earth passes through a dense region of the comet's tail and rates increase five- to ten-fold. In 1982, observers counted 90 Lyrids per hour. Because Thatcher's tail has never been mapped in detail, the outbursts are unpredictable and could happen again at any time. The probabilities are highest during the dark hours before sunrise on April 22nd.
The Moon-Venus conjunction is pure coincidence. It has nothing to do with the Lyrid display other than insurance. Even if the shower fizzles, the sight of a 9% crescent Moon located so close to brilliant Venus is guaranteed to make your day.
Most observers will see only a close gathering of the two bodies. People in western parts of North America are favored with more--a full-blown eclipse or "occultation." Around 5 a.m. Pacific Daylight Time, Venus will disappear behind the mountainous rim of the Moon and reappear 60 to 90 minutes later. Click on the map for local details:
Do not worry if the sun rises during the occultation, because Venus and the Moon are bright enough to see in broad daylight. Locate the pair before sunrise, so you know where they are, then follow them up the brightening sky using binoculars or naked eyes. Some people say Venus and the Moon are most beautiful when surrounded by morning blue.
On Wednesday morning, April 22nd, you can see for yourself.
[ Happy Earth Day!! ]
By: Susie77, 12:47 AM GMT on April 15, 2009
April 14, 2009
MEDIA ADVISORY: M09-058
ONLINE POLL FOR NASA'S GREATEST HITS FOR EARTH BEGINS TODAY
WASHINGTON -- NASA is inviting the public to vote online for the most
important contribution the space agency has made to exploring Earth
and improving the way we live on our home planet. NASA is conducting
the survey as part of its celebration of Earth Day, April 22. Voting
begins today, and closes on April 21. Poll results will be announced
on NASA's Web site on Earth Day.
A 2008 National Research Council study identified major
accomplishments resulting from Earth observations made from space.
The report, "Earth Observations from Space: The First 50 Years of
Scientific Achievements," cataloged scientific discoveries and
practical applications, including many that resulted from NASA
missions, made possible from satellite observations.
NASA selected 10 candidates highlighted in the study for consideration
as the greatest achievements about planet Earth. The options include
diagnosing Earth's ozone layer, predicting food shortages and
tracking ecosystems worldwide. Visitors to the online polling site
will be able to cast their votes for up to three candidate
Since the launch of the United States' first satellite in January
1958, NASA has pioneered the exploration of our home planet from
space. With more than a dozen observation satellites circling the
globe, NASA continues to advance the frontiers of scientific
discovery about Earth, its climate and its future. NASA's
multidisciplinary Earth science program contains a broad-based
portfolio of cutting-edge science and technology, from new
remote-sensing instruments in orbit to basic research.
To cast your votes, visit:
For more information about Earth Day and NASA, visit:
[ Blogger's comment: So which ones did you vote for? ]
By: Susie77, 11:53 PM GMT on April 13, 2009
Space Weather News for April 13, 2009
RADIO STORMS ON JUPITER: On April 11th, an amateur radio astronomer in New Mexico heard loud pops and crackles coming from the loudspeaker of his shortwave receiver. The sounds resembled terrestrial lightning, but the source was not on Earth. It was a radio storm on Jupiter. You can listen to the sounds on today's edition of http://spaceweather.com .
Astronomers have long known that Jupiter produces strong shortwave radio bursts detectable from Earth; the fact of Jupiter's "radio activity" is not news. However, now may be the best time in decades to listen to the giant planet. The sun is in the pits of a century-level solar minimum. Low solar activity increases the transparency of Earth's atmosphere to shortwave radio waves, allowing signals from Jupiter to more easily and clearly reach the ground. At the same time, terrestrial radio interference subsides (another side-effect of solar minimum), so Jupiter bursts are easier to identify.
2009 is going to be a good year for Jupiter. The planet is moving away from the sun and may now be seen shining brightly in the eastern sky before dawn. Students, teachers and amateur scientists who wish to try listening as well as watching should consider building their own radio telescope. Kits are available from NASA's Radio JOVE program: http://radiojove.gsfc.nasa.gov/
[ Blogger's comment: Wouldn't this make a cool science fair project for your student? ]
By: Susie77, 11:48 PM GMT on April 06, 2009
April 06, 2009
National Snow and Ice Data Center, Boulder, Colo.
SATELLITES SHOW ARCTIC LITERALLY ON THIN ICE
WASHINGTON -- The latest Arctic sea ice data from NASA and the
National Snow and Ice Data Center show that the decade-long trend of
shrinking sea ice cover is continuing. New evidence from satellite
observations also shows that the ice cap is thinning as well.
Arctic sea ice works like an air conditioner for the global climate
system. Ice naturally cools air and water masses, plays a key role in
ocean circulation, and reflects solar radiation back into space. In
recent years, Arctic sea ice has been declining at a surprising rate.
Scientists who track Arctic sea ice cover from space announced today
that this winter had the fifth lowest maximum ice extent on record.
The six lowest maximum events since satellite monitoring began in
1979 have all occurred in the past six years (2004-2009).
Until recently, the majority of Arctic sea ice survived at least one
summer and often several. But things have changed dramatically,
according to a team of University of Colorado, Boulder, scientists
led by Charles Fowler. Thin seasonal ice -- ice that melts and
re-freezes every year -- makes up about 70 percent of the Arctic sea
ice in wintertime, up from 40 to 50 percent in the 1980s and 1990s.
Thicker ice, which survives two or more years, now comprises just 10
percent of wintertime ice cover, down from 30 to 40 percent.
According to researchers from the National Snow and Ice Data Center in
Boulder, Colo., the maximum sea ice extent for 2008-09, reached on
Feb. 28, was 5.85 million square miles. That is 278,000 square miles
less than the average extent for 1979 to 2000.
"Ice extent is an important measure of the health of the Arctic, but
it only gives us a two-dimensional view of the ice cover," said
Walter Meier, research scientist at the center and the University of
Colorado, Boulder. "Thickness is important, especially in the winter,
because it is the best overall indicator of the health of the ice
cover. As the ice cover in the Arctic grows thinner, it grows more
vulnerable to melting in the summer."
The Arctic ice cap grows each winter as the sun sets for several
months and intense cold sets in. Some of that ice is naturally pushed
out of the Arctic by winds, while much of it melts in place during
summer. The thicker, older ice that survives one or more summers is
more likely to persist through the next summer.
Sea ice thickness has been hard to measure directly, so scientists
have typically used estimates of ice age to approximate its
thickness. But last year a team of researchers led by Ron Kwok of
NASA's Jet Propulsion Laboratory in Pasadena, Calif., produced the
first map of sea ice thickness over the entire Arctic basin.
Using two years of data from NASA's Ice, Cloud, and land Elevation
Satellite (ICESat), Kwok's team estimated thickness and volume of the
Arctic Ocean ice cover for 2005 and 2006. They found that the average
winter volume of Arctic sea ice contained enough water to fill Lake
Michigan and Lake Superior combined.
The older, thicker sea ice is declining and is being replaced with
newer, thinner ice that is more vulnerable to summer melt, according
to Kwok. His team found that seasonal sea ice averages about 6 feet
in thickness, while ice that had lasted through more than one summer
averages about 9 feet, though it can grow much thicker in some
locations near the coast.
Kwok is currently working to extend the ICESat estimate further, from
2003 to 2008, to see how the recent decline in the area covered by
sea ice is mirrored in changes in its volume.
"With these new data on both the area and thickness of Arctic sea ice,
we will be able to better understand the sensitivity and
vulnerability of the ice cover to changes in climate," Kwok said.
For more information about Arctic sea ice, visit:
For more information about NASA and agency programs, visit:
By: Susie77, 12:56 AM GMT on April 03, 2009
Space Weather News for April 2, 2009
100 HOURS OF ASTRONOMY: This week, astronomers are celebrating the 400th anniversary of Galileo's original telescopic exploration of the sky with "100 Hours of Astronomy," a cornerstone project of the International Year of Astronomy. Running from April 2 through April 5, many different public programs are planned worldwide. Is one of them near you? Visit the 100 Hours web site to find out: http://www.100hoursofastronomy.org/ Note that the celebration ends on Sun Day, April 5th, a special date devoted to observations of the sun: http://solarastronomy2009.org/100-hours-sunday/ .
By: Susie77, 6:40 PM GMT on April 01, 2009
Deep Solar Minimum
April 1, 2009: The sunspot cycle is behaving a little like the stock market. Just when you think it has hit bottom, it goes even lower.
2008 was a bear. There were no sunspots observed on 266 of the year's 366 days (73%). To find a year with more blank suns, you have to go all the way back to 1913, which had 311 spotless days: plot. Prompted by these numbers, some observers suggested that the solar cycle had hit bottom in 2008.
Maybe not. Sunspot counts for 2009 have dropped even lower. As of March 31st, there were no sunspots on 78 of the year's 90 days (87%).
It adds up to one inescapable conclusion: "We're experiencing a very deep solar minimum," says solar physicist Dean Pesnell of the Goddard Space Flight Center.
"This is the quietest sun we've seen in almost a century," agrees sunspot expert David Hathaway of the Marshall Space Flight Center.
Quiet suns come along every 11 years or so. It's a natural part of the sunspot cycle, discovered by German astronomer Heinrich Schwabe in the mid-1800s. Sunspots are planet-sized islands of magnetism on the surface of the sun; they are sources of solar flares, coronal mass ejections and intense UV radiation. Plotting sunspot counts, Schwabe saw that peaks of solar activity were always followed by valleys of relative calm—a clockwork pattern that has held true for more than 200 years: plot.
The current solar minimum is part of that pattern. In fact, it's right on time. "We're due for a bit of quiet—and here it is," says Pesnell.
But is it supposed to be this quiet? In 2008, the sun set the following records:
A 50-year low in solar wind pressure: Measurements by the Ulysses spacecraft reveal a 20% drop in solar wind pressure since the mid-1990s—the lowest point since such measurements began in the 1960s. The solar wind helps keep galactic cosmic rays out of the inner solar system. With the solar wind flagging, more cosmic rays are permitted to enter, resulting in increased health hazards for astronauts. Weaker solar wind also means fewer geomagnetic storms and auroras on Earth.
A 12-year low in solar "irradiance": Careful measurements by several NASA spacecraft show that the sun's brightness has dropped by 0.02% at visible wavelengths and a whopping 6% at extreme UV wavelengths since the solar minimum of 1996. These changes are not enough to reverse the course of global warming, but there are some other, noticeable side-effects: Earth's upper atmosphere is heated less by the sun and it is therefore less "puffed up." Satellites in low Earth orbit experience less atmospheric drag, extending their operational lifetimes. That's the good news. Unfortunately, space junk also remains longer in Earth orbit, increasing hazards to spacecraft and satellites.
A 55-year low in solar radio emissions: After World War II, astronomers began keeping records of the sun's brightness at radio wavelengths. Records of 10.7 cm flux extend back all the way to the early 1950s. Radio telescopes are now recording the dimmest "radio sun" since 1955: plot. Some researchers believe that the lessening of radio emissions is an indication of weakness in the sun's global magnetic field. No one is certain, however, because the source of these long-monitored radio emissions is not fully understood.
All these lows have sparked a debate about whether the ongoing minimum is "weird", "extreme" or just an overdue "market correction" following a string of unusually intense solar maxima.
"Since the Space Age began in the 1950s, solar activity has been generally high," notes Hathaway. "Five of the ten most intense solar cycles on record have occurred in the last 50 years. We're just not used to this kind of deep calm."
Deep calm was fairly common a hundred years ago. The solar minima of 1901 and 1913, for instance, were even longer than the one we're experiencing now. To match those minima in terms of depth and longevity, the current minimum will have to last at least another year.
In a way, the calm is exciting, says Pesnell. "For the first time in history, we're getting to see what a deep solar minimum is really like." A fleet of spacecraft including the Solar and Heliospheric Observatory (SOHO), the twin STEREO probes, the five THEMIS probes, ACE, Wind, TRACE, AIM, TIMED, Geotail and others are studying the sun and its effects on Earth 24/7 using technology that didn't exist 100 years ago. Their measurements of solar wind, cosmic rays, irradiance and magnetic fields show that solar minimum is much more interesting and profound than anyone expected.
Modern technology cannot, however, predict what comes next. Competing models by dozens of top solar physicists disagree, sometimes sharply, on when this solar minimum will end and how big the next solar maximum will be. Pesnell has surveyed the scientific literature and prepared a "piano plot" showing the range of predictions. The great uncertainty stems from one simple fact: No one fully understands the underlying physics of the sunspot cycle.
Pesnell believes sunspot counts will pick up again soon, "possibly by the end of the year," to be followed by a solar maximum of below-average intensity in 2012 or 2013.
But like other forecasters, he knows he could be wrong. Bull or bear? Stay tuned for updates.
Here's info on what happens during