There’s been some action on the aurora scene today. A coronal mass ejection from the sun blew by Earth this afternoon and sparked auroras over northern Scandinavia and other locations in northern Europe where it was dark at the time. There’s continues to be a fair chance for minor auroras over the northern U.S. tonight (Sun. April 20-21), so you may want to be on the lookout. Check the Ovation Aurora site to see the extent of the aurora in near real time.
We celebrate Earth Day this upcoming Tuesday, a time to reflect on how each of us can better our environment. It also happens to be the peak of the annual Lyrid meteor shower.
The Lyrids reliably shoot from the sky every mid to late April, peaking overnight April 21-22 this year. I’ve seen the Lyrids on a couple occasions and can vouch that it’s a reliable though not particularly rich meteor shower. Normal rates are 10 to 20 meteors per hour, but light from the last quarter moon will reduce this year’s count to 5-10 per hour.
The greatest number of meteors are seen when the radiant, the point in the sky from which they appear to stream, is highest. That occurs just before dawn Tuesday morning. But because the moon doesn’t rise until 2-2:30 a.m., you might do just as well catching the Lyrids from midnight till 2. The radiant will be moderately high in the east and the sky still dark.
While the Lyrids implies an association with the constellation Lyra, home to the brilliant star Vega, the meteors shoot from a location in eastern Hercules 7 degrees southwest of Vega. Each one you see is small bit of dust or rock left behind by Comet Thatcher which last appeared in 1861 and won’t again until 2276.
Each April, Earth passes through Thatcher’s stream of debris and we see the pieces flare as meteors when they strike the air overhead.
Their average speed is 105,000 mph (169,000 km/hr). That’s almost 3 times faster than the current fastest moving spacecraft in the solar system, Voyager 1, at 38,000 mph (61,000 km/hr).
Not a major shower, the Lyrids still occasionally surprise with fireballs and rich outbursts of meteors. Counts were much higher than normal in 1803, 1849, 1850, 1884, 1922, 1945, and 1982. Both Ludwig von Beethoven and famous astronomer William Herschel were around for the 1803 Lyrids which topped out at more than 500 per hour!
To watch the shower, either take the ‘early shift’ from midnight-2:30 a.m. and face east or dare to challenge the moon between 2 and dawn when Hercules and Vega are high in southern sky. I usually spice up my meteor watching with a look through the telescope at the bright planets. Mars shines due south now around midnight with Saturn further off to the southeast.
One final note. The moon will be very close to the star Beta in Capricornus Tuesday morning. Take a look at it in binoculars. If you live in the western half of the U.S., Beta will be occulted by the moon around 4:30 a.m. Mountain time, 3:30 a.m. Pacific. Midwesterners might still see it in bright twilight around 5:30 a.m. with a small telescope. Look immediately to the left of east of the moon’s bright edge.
Invite a friend to join you, boil up some tea and relax under the stars. Every meteor you see is a gift.
What it may sound like a huge disaster, destroying the $263 million dollar spacecraft was NASA’s intention from the start. At 8:59 p.m. CDT April 17, the agency confirmed the probe had impacted the moon’s surface.
The Lunar Atmosphere and Dust Explorer or LADEE (pronounced ‘laddie’) began circling the moon last fall, its mission to study dust in its extremely rarefied lunar atmosphere. Much of the dust sputters off the surface during meteorite impacts, while some may be lofted into the sky by electrostatic forces active when the sun rises along the day-night borderline called the terminator.
Prior to crashing, mission controllers gradually lowered the spacecraft’s orbit to study the moon’s near surface dust environment in ever more detail. While the moon lacks the atmosphere to slow a spacecraft and “drag” it down to the surface (like what happens at Earth), nature worked her wonders all the same. The moon’s gravity field is “lumpy”, with lighter, less dense regions alternating with denser concentrations of rock beneath the surface. Low-orbiting probes, perturbed by variations in pull of gravity are soon brought down.
“At the time of impact, LADEE was traveling at a speed of 3,600 miles per hour – about three times the speed of a high-powered rifle bullet,” said Rick Elphic, LADEE project scientist at Ames. “There’s nothing gentle about impact at these speeds — it’s just a question of whether LADEE made a localized craterlet on a hillside or scattered debris across a flat area. It will be interesting to see what kind of feature LADEE has created.”
NASA plans to work with the Lunar Reconnaissance Orbiter (LRO) team to overfly and capture an image of the impact site. LADEE struck the moon on the farside, a safe distance from any historic landing sites, all of which have been on the lunar nearside. Because radio communications can’t be received from the farside, NASA mission controllers had to wait for an hour during each ultra-low orbital pass. If LADEE began sending data again, they knew it was still “alive”. When LADEE didn’t show up at the planned time Thursday, the mission was declared over.
Scientists will be analyzing the data from the probe for a long, long time, but there are some preliminary results:
* LADEE survived the chill-inducing lunar eclipse earlier this week, demonstrating the spacecraft’s ability to endure low temperatures and a drain on batteries as it, and the moon, passed through Earth’s deep shadow.
* LADEE’s Lunar Dust EXperiment (LDEX) experiment detected an increase in the number of dust particles in the moon’s exosphere during the Geminid meteor shower in mid-December 2013. The LDEX dust impacts are thought to be due to the ejecta, or spray, of particles that result when the Geminid meteoroids slam into the lunar surface. The exosphere or dilute lunar atmosphere contains dust particles as well as gases from the solar wind.
* The Ultraviolet and Visible light Spectrometer (UVS) carried out a series of before and after observations looking for effects of the Chinese Chang’e 3 landing in December and meteor showers. Analysis revealed an increase in sodium connected with the Geminids, as well as evidence of increased light scattering due to dust but no clear signal from the Chang’e 3 landing.
The UVS also has been monitoring specific wavelengths of light emitted by atomic oxygen, and has seen emissions that may indicate the presence of both iron and titanium in the lunar exosphere. All three are elements found in the lunar soil called regolith but have never been seen in the moon’s atmosphere before.
I can’t recall seeing the sun this peppered with sunspots in a long time. Through the scope this morning I counted nine separate groups. No single spot or group stood out as unusually large, but the combined effect of seeing so many blemishes in one glance made an impression. I encourage you to point your telescope – suitably equipped with a safe solar filter of course – at the sun today to appreciate how fraught with magnetic activity our sun has become.
Each group marks a region on the sun’s shiny outer skin called the photosphere where magnetic energy is concentrated. Strong magnetic fields within a sunspot group quell the turbulent churning of the photosphere, chilling the region by several thousand degrees. Sunspots appear dark against the sun’s blazing disk because they’re cooler.
Energy stored in sunspots’ twisted magnetic fields can suddenly be released in violent, explosions called solar flares. Billions of tons of solar plasma – the sizzling mix of protons and electrons that composes the sun – are heated to millions of degrees during the explosion and rapidly accelerated into space. Radiation from radio waves to X-rays and gamma rays fan out at the speed of light. Fortunate for us, our atmosphere and planetary magnetic field protect us from most of what flares can dish out.
Not everything though. Strong X-class flares can cause radio blackouts, damage satellite electronics and disrupt poorly protected power grids. They also can spark displays of northern lights. An M-class flare from sunspot region 2035 on April 16 may kick off auroras overnight Saturday April 19-20. NOAA forecasters predict a 25% chance of a minor auroral storm.
Video of February’s X4.9 flare shown in multiple wavelengths of light
Conditions are ideal if it comes to pass. Moonlight won’t be a problem and night temperatures are decidedly more pleasant than in February.
We’ve come a long way. First it was only giant planets seared by hot proximity to their host stars. Not anymore. Astronomers announced the discovery today of the first Earth-sized planet in the “habitable zone” of its host star. Habitable, when it comes to extra-solar planets, means the right distance for liquid water to pool on the planet’s surface. Water is intimately tied to life on Earth and may also be on other worlds.
Other planets have been discovered in their stars’ habitable zones, but they’ve all been at least 40% larger than Earth. This one, named Kepler-186f, nearly matches Earth in size and orbits Kepler-186, a star with four previously known planets 500 light years away in the constellation Cygnus (Northern Cross).
“Being in the habitable zone does not mean we know this planet is habitable,” cautions Thomas Barclay, a research scientist at the Bay Area Environmental Research Institute at Ames, and co-author of the paper. “The temperature on the planet is strongly dependent on what kind of atmosphere the planet has. Kepler-186f can be thought of as an Earth-cousin rather than an Earth-twin. It has many properties that resemble Earth.”
Kepler-186f is 10% larger than Earth and orbits an M class red dwarf star every 130 days, soaking in just one-third the amount of heat Earth receives from the sun. That places it near the edge of the habitable zone. Its mass and composition are still unknown, but previous studies imply planets this size are made of rock like Earth.
Transiting Exoplanet Survey Satellite (TESS) – the next generation in exoplanet discovery
The Kepler space telescope infers the existence of a planet by the amount of starlight blocked when it passes in front of its host star. From these data, a planet’s size, orbital period and the amount of energy received from the host star can be determined. Before an equipment failure, Kepler observed nearly 150,000 stars simultaneously looking for dips in the stars’ light made by orbiting planets.
To date, about a thousand planets have been confirmed with the Kepler data with another nearly 3,000 unconfirmed candidates.
“Future NASA missions, like the Transiting Exoplanet Survey Satellite and the James Webb Space Telescope, will discover the nearest rocky exoplanets and determine their composition and atmospheric conditions, continuing humankind’s quest to find truly Earth-like worlds,” said Paul Hertz, NASA’s Astrophysics Division director.
Like we often do in our personal lives, we’re looking for someone like us. Earth’s twin is out there. We’re getting closer.
Venus occults or covers the star Lambda Aquarii April 17, 2014
A planet covering a naked eye star is rarer by far than a total eclipse of the moon, and yet Venus did just that yesterday afternoon (U.S. time) from Australia, New Zealand and Micronesia. No one in the northern hemisphere witnessed the event; Venus passed south of the star from our perspective.
Jonathan Bradshaw of Australia captured this exceptional alignment well in his video despite the shaky atmosphere. Lambda Aquarii, a 4th magnitude star in Aquarius, was wiped from the sky for all of seven minutes.
It’s believed that the last bright star Venus or any major planet covered up was 2nd magnitude Nunki in Sagittarius for observers in eastern Africa in November 1981. Venus next occults Pi Sagittarii in 2035 and bright Regulus on Oct. 1, 2044. Mercury will cover up Theta Ophiuchi on Dec. 4, 2015.
Very rarely, planets pass in front of each other. Over the 300 year span from 1800 to 2100 only 7 “mutual occultations” of this sort have or will occur. Venus crossed in front of Jupiter in 1818 – that was the last observable one. The next will happen when Mars passes in front of Jupiter on Dec. 2, 2223. Clearly, you and I and even our kids won’t be around for that event, but maybe some of our kids’ kids will.
Nature shows that once again even the most unlikely things can happen as long as one key ingredient is available – oodles of time.
No way is the moon done serving up delights. Tireless as ever even after a long slog through Earth’s shadow Monday night, it lifts our gaze to the planet Saturn tonight.
Look moon-ward after 11 o’clock tonight and bang – Saturn will be right in front of your nose. The two worlds are in conjunction this evening and paired up very close to one another in the southern sky.
Moonrise happens around 10 p.m. but I’d suggest you wait until after 11 to see them best. From most locations, the two will be only about a degree apart.
Glare made seeing Spica before last night’s eclipse challenging unless you covered the moon with your thumb. Saturn and the moon will be just as close tonight, but the moon’s slimmed and dimmed since full and Saturn’s brighter than Spica, so you should have no problem seeing them side by side.
Use the opportunity to point your telescope at the planet famous for its hula hoop act. Saturn will be brightest and closest for the year on May 10 when it reaches opposition. Just as with Mars and the other outer planets, opposition is the time when a planet lines up with Earth on the same side of the sun. This cozy familiarity brings the planet into bright view. 10x binoculars will reveal the planet’s oval shape (thanks to the extra added width of the rings), and a small telescope magnifying 40x will bring at least one ring into clear view.
Most skywatchers would agree that Saturn is most attractive when the rings are tilted near their maximum. During planet’s 29.5 year orbit around the sun, their inclination to Earth varies from 0 degrees (edge-on) to 27 degrees. This month we see the north face of the rings tilted near maximum at 21.7 degrees.
Open rings means you can spot Saturn’s biggest ring gap called Cassini’s Division more easily now than anytime in the past few years. Named after Giovanni Cassini, a Italian/French astronomer who discovered the division and four of Saturn’s moons back in 1675, this “clear zone” spans some 3,000 miles (4,800 km) and separates the bright, wide B Ring from the narrower A Ring.
Spacecraft like NASA’s Cassini probe, which has been orbiting and studying the planet since 2004, have revealed that the gap isn’t as vacant as it appears. As far back as 1980, the Voyager 1 probe showed that that Cassini’s Division contains material similar to that found in the less massive C Ring. It’s even organized into multiple concentric rings divided by yet finer gaps.
Wishing you a happy night.
What a fine eclipse! I hope you were as fortunate as we were to have clear skies. Here are a few photos taken during a very long night with my friend Will. After looking at and photographing the moon through the telescope in the countryside, we set off for the city to see how a big red ball paired with familiar scenes.
I first noticed the penumbral or outer shadow of the Earth about a half hour before partial eclipse as a brownish shading along the moon’s left side. The edge of the inner, dark shadow – called the umbra – was fuzzy and smoky orange-brown in the telescope. What fun to watch it creep over the moon’s face covering one crater after another.
During total eclipse, the top of the moon, which was closest to the center of the umbra was very dark orange with the naked eye, while the bottom rind – the portion of the moon farthest from umbral center – glowed a dull yellow. Colors varied some depending on whether you viewed with the naked eye, binoculars or telescope.
One of our favorite sights was seeing the totally eclipsed moon alongside its starry companion Spica in binoculars. In the 8×40 glass, the moon looked pumpkin-colored. My older daughter said the eclipsed moon looked like a toasted marshmallow!
As the moon progressed through the umbra, a yellow “smile” of a crescent slowly slid from one side to the other along the moon’s bottom edge. A minute after emerging from totality, the brilliant “cap” of light on the moon’s left side resembled a polar cap on the red planet Mars. What a fine coincidence the real Mars was just a fist away.
A favorite pastime during total lunar eclipses is watching the darkness return as the moon gets clipped by Earth’s shadow. The change is slow at first but soon you’re staring up marveling at how all those stars got there. During totality the sky’s was as dark as a moonless night and stayed that way for over an hour.
When moonlight returned, the stars fled and the Milky Way faded away in the lunar glare … until the next eclipse in October! Thank you everyone for sharing your images. I also encourage you to continue to share your impressions in the Comments section below.
That bright swelling in Saturn’s A ring may very well be ice balls stirred up by a newborn moon nicknamed ‘Peggy’. Estimated at just a half-mile (1 km) across, the newcomer could be the first moon ever seen to form right before our eyes.
Images taken by the Cassini probe April 15, 2013, revealed several disturbances at the very edge of Saturn’s A ring, the outermost of the planet’s large, bright rings. One of them is the arc shown above that’s about 20 percent brighter than its surroundings and spans some 750 miles (1,200 km) long by 6 miles (10 km) wide. It even sports a little bump that interrupts the smooth profile of the ring’s edge.
“We have not seen anything like this before,” said Carl Murray of Queen Mary University of London, the report’s lead author. “We may be looking at the act of birth, where this object is just leaving the rings and heading off to be a moon in its own right.”
The object probably won’t grow any larger and in fact, may even be falling apart according to astronomers. Like the rings, many of Saturn’s moons are composed of ice. It’s believed that long ago, the rings were larger and more massive and gave rise to larger moons like Enceladus and Titan in a similar birthing process. Today these moons are relatively far from the planet but may have migrated there after self-assembling via gravity within the ring plane.
As exciting as the birth of a new moon is, I find it equally fascinating that Saturn’s ring system may serve as a model of the early solar system when it was little more than rings of rocky and icy debris surrounding the infant sun. From these dribs and drabs, all the planets, comets and asteroids took form.
We’re almost certain that most if not all the planets migrated through this debris-strewn traffic jam similar to what appears to have happened at Saturn. Earth and the inner planets were likely farther from the sun billions of years ago and migrated inward, while Jupiter and Saturn took off in the opposite direction.
“Witnessing the possible birth of a tiny moon is an exciting, unexpected event,” said Cassini Project Scientist Linda Spilker, of NASA’s Jet Propulsion Laboratory. According to Spilker, Cassini’s orbit will move closer to the outer edge of the A ring in late 2016 and provide an opportunity to study Peggy in more detail. Maybe even take a picture.
If theory is proven true then Saturn’s rings are much depleted after a life of making moons, leaving only enough material left to fashion a mini-moon or two.
I’m rooting for Peggy to step out of the shadows and lead a life of her own. How wonderful it would be to witness the birth of a new Saturnian moon in our lifetime.
I’m excited. Beginning late tonight and continuing into the small hours tomorrow morning, skywatchers across the Americas will have ringside seats for one of nature’s most unique and colorful celestial events – a total eclipse of the moon.
Anyone hoping to see the eclipse will be paying attention to the local forecast. Weather really can mess with your head. While you can perform chemistry experiments clear or overcast, astronomy requires the fickle cooperation of Mother Nature. Remember last month’s widely-publicized occultation of Regulus by the asteroid Erigone? One of the rarest events to occur in years, clouds, snow and rain made sure that no one – not a single person to date – got to see it.
Today’s satellite weather map shows widespread clouds across the eastern third of the country but clear or clearing skies will be the rule across the western and central U.S. To get a local forecast, click HERE and enter your zip code or city name.
You can also consult Attila Danko’s Clear Sky Chart. Type in your city to get a detailed cloud/transparency forecast I’ve found to be surprisingly accurate.
Just to refresh, a lunar eclipse occurs when the sun, Earth and moon are precisely lined up in a row at the time of full moon. Watching the moon slowly disappear will make even those who don’t pay much attention to the sky turn to look. The event begins with a brilliant full moon that disappears by degrees into the shadow until it hangs suspended among the stars like a dark cherry. Beautiful!
If you get skunked by bad weather, several organizations will be streaming the eclipse live. Here’a s few to check out:
* NASA TV live – Commentary and coverage begin at midnight CDT Tuesday morning
* SLOOH – Coverage begins 1 a.m. CDT
* Virtual Telescope Project begins 1:30 a.m. CDT
Use a tripod-mounted camera to photograph the moon during the partial phases with exposures ranging from 1/250 (bright moon) to 1/8 second (closer to totality) with the lens opened to f/5.6 – f/8.
Increase your exposure to 4-5 seconds (or longer – depends on how dark this eclipse will be) and set your lens aperture to f/4 – f/5.6. These are general guidelines using ISO 400. As always, experiment.
I know there are lots of places to share images these days, but if you get one you like, I’d be happy to post it here on Tuesday. Just send an e-mail to email@example.com with ‘Eclipse photo’ in the subject box. Thanks!
Below is a table with the times for all key eclipse events across the four major U.S. time zones beginning with the first hint of shading from Earth’s outer shadow, the penumbra. And here’s a link to more eclipse information.
Eclipse Events EDT CDT MDT PDT
|Penumbra visible||1:20 a.m.||12:20 a.m.||11:20 p.m.||10:20 p.m.|
|Partial eclipse begins||1:58 a.m.||12:58 a.m.||11:58 p.m.||10:58 p.m.|
|Total eclipse begins||3:07 a.m.||2:07 a.m.||1:07 a.m.||12:07 a.m.|
|Mid-eclipse||3:46 a.m.||2:46 a.m.||1:46 a.m.||12:46 a.m.|
|Total eclipse ends||4:25 a.m.||3:25 a.m.||2:25 a.m.||1:25 a.m.|
|Partial eclipse ends||5:33 a.m.||4:33 a.m.||3:33 a.m.||2:33 a.m.|
|Penumbra visible||——–||5:10 a.m.||4:10 a.m.||3:10 a.m.|