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Soon you may see an eerie spectacle on clear summer nights if you are located at latitudes between 50° and 70° north and south of the equator: Noctilucent Clouds.

These ghostly apparitions are a delight to see and are quite rare. It is incredibly difficult to predict exactly when they will appear, but we do know they should begin to appear soon.

The season for Noctilucent Clouds (Noctilucent = Latin for “Night Shining”) starts early June and continues into late July. They are seen just after dusk, or before dawn and an apparition can last around an hour.

These mysterious clouds, with their bizarre tenuous wispy shapes reminiscent of ripples in sand or the changing surface of a pool of water, spread like a glowing web across the northern sky. Colours can range from brilliant whites, with tinges of blue, pink and orange.

Formed by tiny ice crystals, they are the highest clouds in the Earth’s atmosphere, located in the mesosphere at altitudes of around 76 to 85 kilometers (47 to 53 miles) almost at the edge of space.

They are normally too faint to be seen, and are visible only when illuminated by sunlight from below the horizon, while the lower layers of the atmosphere are in the Earth’s shadow. Noctilucent clouds are not fully understood and are a recently discovered meteorological phenomenon, only being recorded for about 120 years.

Noctilucent clouds can only form under very restrictive conditions, and their occurrence can be used as a guide to changes in the upper atmosphere. Since their relatively recent classification, the occurrence of noctilucent clouds appears to be increasing in frequency, brightness and extent.

There is evidence that the relatively recent appearance of noctilucent clouds and their gradual increase, may be linked to climate change. Another recent theory is that some of these bright displays come from particulates and water vapour in the atmosphere left over from Space Shuttle launches.

How can you see them? Over the next couple of months look north during dusk and dawn and try and spot this mysterious and elusive phenomenon. They are best seen when the sun is between 6 and 16 degrees below the horizon, and seem to occur more frequently in the Northern hemisphere than the Southern.

Good luck!

I am often asked or hear about bright fireballs in the sky, often reported by non astronomy minded people, so when you ask where was it and what direction it was travelling etc, you get very sketchy information back like: It was over my house and headed towards town, I think?
Only if you have many sightings of the same fireball can you interpolate where it was and what direction etc it was travelling? Things are going to be made a lot easier if you live in some parts of the United States.

NASA is building a network of "Meteor Cameras" in a few of States in the US called the "All-sky Fireball Network". This is a network of cameras set up by the NASA Meteoroid Environment Office (MEO) with the goal of observing meteors brighter than the planet Venus, which are called fireballs.  The collected data will be used by the MEO in constructing models of the meteoroid environment, which are important to spacecraft designers.

The Network will eventually consist of up to 15 overlapping cameras in north Alabama, northwest Georgia, and southern Tennessee, placed on public buildings and schools. The network will use sensitive black and white cameras which are able to see the whole of the sky (All Sky).
Because the cameras have overlapping fields of view, more than one camera can see the same meteor at the same time, helping in getting data about its trajectory and with clever data collection software, ascertain if the meteor came from a comet or an asteroid.
 

NASA’s All-sky Fireball Network uses ASGARD (All Sky and Guided Automatic Realtime Detection). ASGARD not only handles all the data processing (which is considerable) it also automatically pushes the results to the web. See the results here: http://fireballs.ndc.nasa.gov

Originally posted on Sky and Telescope by by Kelly Beatty, October 6, 2010

Everyone enjoys a great meteor shower, those special times each year when a profusion of shooting stars zip across the sky. So here's a head's up: all of you should circle October 8th on next year's calendar.

This is the yearly date when Earth plows through a tenuous band of space dust created by Comet Giacobini-Zinner along its orbit. Ordinarily, the Draconid shower (formerly called the Giacobinids) puts on a so-so celestial show, delivering about 20 meteors per hour if you can view them under a moonless, pitch-black sky. That's hardly worth staying up for: after all, from a similarly clear, dark site you'll see six or seven random ("sporadic") meteors per hour.

However, this shower has a Jekyll-and-Hyde personality. In 1933 and 1946 the Draconids dazzled skywatchers with astounding meteor "storms" — delivering shooting stars at rates that briefly topped 10,000 per hour! — because Earth crossed through a particularly dense ribbon of debris shed by the comet in 1900. The shower hasn't put on that kind of performance in the years since, though in 2005 it surged unexpectedly to double or triple the usual rate.

If celestial prognosticators are right, we're in for a treat next year, when Draconid rates could top 600 per hour — that's 10 per minute — under ideal viewing conditions. That surge is in the cards because we'll likely clip the stream of particles ejected in 1900. Odds are that it's still largely intact, even though the comet's 6½-year-long orbit periodically puts it in Jupiter's disruptive vicinity.
 

On October 8, 2011, Earth will pass through several streams of particles ejected over the past 200 years by Comet Giacobini-Zinner.

J. Vaubaillon & others

At a meeting of planetary scientists now under way in Pasadena, California, meteor dynamicist Jérémie Vaubaillon (IMCEE, France) put forth predictions that he'd calculated with colleagues Mikiya Sato and Jun-ichi Watanabe (NAOJ, Japan). If they're right, next October 8th Earth crosses some cometary debris shed by Comet G-Z between 1873 and 1894, peaking at perhaps 60 meteors per hour centered at 17:09 Universal Time, followed at 19:57 UT by a much stronger, 600-per-hour pulse from the 1900 stream.

The rate is very uncertain, Vaubaillon admits, because there's no way to know whether those earlier streams are still densely packed or have been spread thin. Meteor observing wasn't as rigorous back then as it is now. But next year's results should help disentangle which streams are still contributing to the overall rates.

Other meteor specialists are also struggling to come up with firm rates. In 2008 Sato and Watanabe independently estimated a maximum of 500 per hour (at 20:36 UT), whereas NASA researchers Danielle Moser and William Cooke have offered a more optimistic 800 per hour (at 19:11).

These times favor observers in Europe, but don't rush out to book a plane just yet. First, the Draconid shower tends to produce many faint meteors that'll be obliterated by a nearly full Moon that night.
 

Although Europe is favored for watching the 2011 Draconid meteor shower, this map of average cloud cover during October suggests finding clear skies might prove challenging. (Bluer hues denote more frequent clouds.) Click on the image for a larger view.

Jay Anderson

Second, because the shower's radiant is way up near the head of Draco (declination +54°), the best observing sites would likewise be geographically north. But there's a reason that so few people book vacations to Scandinavia in October: "Weather in Northern Europe is not very pretty," notes Canadian meteorologist Jay Anderson. "October can be very nice, but usually it is the time when the winter cloudiness begins to encroach on the daily weather."

Instead, Anderson's cloud-cover map (at right) suggests that the northernmost "good weather" spot is in the Greek Islands. "Santorini — a favorite place of mine — has clear/few/scattered cloud cover 74% of the time. I know where I'd go."

Originally posted on Dark Sky Diaries by Steve Owens (@darkskyman on Twitter)

With the Quadrantids meteor shower that has just past yielding around 100 meteors per hour in near-perfect New Moon conditions, which showers of the next two years will give us as good a display?

Meteor Shower

There are a few regular, dependable showers that can be relied on to put on a good show year after year, given a good Moon phases, so let’s concentrate on those:

Lyrids 2011
The Lyrids peak this year on April 21/22, only three days after the Full Moon, making conditions far from ideal. The ZHR is around 20, but under bright Moon conditions this will be much reduced, so that from the UK you might only see a few Lyrids per hour.

Persieds 2011
The Perseids peak on 12/13 August 2011 coincides exactly with a Full Moon, making this shower pretty much a write-off in 2011.

Orionids 2011
The Orionids peak occurs on 21/22 October 2011 just after the last quarter Moon, with the Moon rising a little after midnight, just as the meteor shower radiant is gaining height. Again, far from ideal.

Leonids 2011
The Leonids peak on 17/18 November occurs during a last quarter Moon, which unfortunately is smack bang in the direction of Leo, and so will obscure many of the Leonids in 2011

Geminids 2011
The Geminids peak on 13/14 December 2011 will likewise be completely obscured by an almost-full Moon in Gemini.

Quadrantids 2012
The Quadrantids peak on 3/4 January 2012 will feature a waxing gibbous Moon which won’t set until 0400.

Lyrids 2012
The Lyrids peak on 21/22 April 2012 is the first major shower peak in 15 months where the Moon is absent, meaning that you should get good views of this shower which has a ZHR of only around 20.

Persieds 2012
The Perseids peak of 12/13 August 2012 will feature a thin waning crescent moon that’s visible in the sky from midnight, obscuring some of the Perseids.

Orionids 2012
The Orionids peak on 21/22 October 2012 is pretty much Moon-free from around 2330, as the Moon sets.

Leonids 2012
The Leonids peak on 17/18 November 2012 will also be Moon free from early evening, and so presents an opportunity to see a few Leonids.

Geminids 2012
Rounding off this two year run of poor Moon conditions for meteor showers, we end with the Geminids on 13/14 December, coinciding wonderfully with a New Moon on 13 December, meaning conditions will be near perfect.

Originally posted on Dark Sky Diary by Steve Owens www.twitter.com/darkskyman

The first meteor shower of 2011 is the Quadrantids, the peak of which falls on the night of the 03/04 January 2011. The Quadrantids shower has one of the highest predicted hourly rates of all meteor showers, comparable to the two great annual showers, the Perseids and the Geminids, occurring in August and Deember respectively. However unlike the Perseids and Geminids, the Quadrantids peak is very narrow, occurring over just a few short hours.  (You can read the IMO’s rather technical summary of the 2011 Quadrantids here: http://www.imo.net/calendar/2011#qua)

The predicted Zenith Hourly Rate (see my previous post about ZHR and what it actually means here) for the Quadrantids is around 120. The narrow peak is predicted to occur some time between 2100 on 3 January and 0600  on 4 January 2011, however the radiant of the shower – the now-defunct constellation Quadrans Muralis – is very low in the evening hours, rising higher towards dawn, and so the best viewing times are later in this run, just before dawn.

The radiant will rise due N and get to its highest before dawn due E, so look roughly in a NE direction to maximise your chance of seeing some Quadrantids. As always with meteor showers, don’t use binoculars or a telescope – your naked eyes are best. One very useful bit of equipment is a reclining deck chair, which makes observing so much more comfortable!

Let’s use the equation relating ZHR to actual observations of meteors to work out how many Quadrantids you might see:

Actual Hourly Rate = (ZHR x sin(h))/((1/(1-k)) x 2^(6.5-m)) where

h = the height of the radiant above the horizon

k = fraction of the sky covered in cloud

m = limiting magnitude

In the case of the 2011 Quadrantids, if observed from the UK, h = 15 degrees at 2100, rising to 25 degrees at midnight, 40 degrees at 0300, and 65 degrees at 0600. Let’s assume you have clear skies (haha) with k = 0.

The number of Quadrantids you can expect to see from a variety of observing sites, at various times throughout the night, is as follows:

For very light polluted sites, such as city centres, m = 3, and therefore you can expect to see between 3 and 10 meteors per hour at the peak, depending on when it occurs.

In suburban skies near a city or town centre m = 4, and you’ll see between 5 and 20 meteors per hour at the peak, depending on when it occurs.

In rural skies where m = 5, you’ll see between 11 and 38 meteors per hour at the peak, depending on when it occurs.

Under very dark skies, where m = 6.5 (i.e. where there is no or negligible effect of light pollution, like in Galloway Forest Dark Sky Park) you’ll see anywhere between 31 and 109 meteors per hour at the peak, depending on when it occurs.

Remember, all of these numbers assume perfectly clear skies. If half your sky is cloudy, cut these numbers in half!

Also remember that it depends when the peak occurs. Due to the rather narrow peak, if you observe at 2100 on 3 January you may see very few if the peak doesn’t occur until 0600. Still, it’s very much worth a look, just in case!

How many Quadrantid meteors will I see?

This full frame image was taken on the 14th of December from Cemaes Bay on
Anglesey looking East by Kev Lewis

Canon 5D MkII and Canon 24mm f1.4L lens shooting 20 second exposures at
f2.8 iso 1600

http://www.photosbykev.com

Originally posted on the 10th December 2010 by AstroGuys

http://astroguyz.com/2010/12/10/astro-event-don%E2%80%99t-miss-the-geminids/

Looking Northeast at about 10 PM. (Photo by Author).

   This year, believe the hype; this month’s Geminid meteor shower is a sure bet. This shower is one of the few dependable ‘old faithful’ meteor showers of the year. Peaking on the night of December 13^th-14^th, this year’s apparition sees a well placed northern radiant rising high in the northeast as the first quarter Moon sets about midnite local. The Geminid stream radiates from very near the bright star Castor in the zodiac constellation Gemini the Twins and typically produces up to 100 to 120 meteors per hour. If you are placed in mid-northern latitudes, you may see some activity shortly after sunset, but the real meteoritic action will begin after midnite. Think of a car driving at night in a snowstorm, not a stretch in the depths of the northern hemisphere winter. Looking forward into your high beams you get the cool vintage “Star Trek” effect, as you and your vehicle plow headlong into the stream of snowflakes. Think of the flakes as meteors and the car as the Earth; we face headlong into the meteor stream after midnight, and hence see more flashing meteor trains. The Geminids present several swift movers and fireballs, and the darker skies you have access to, the more you’ll see. Be sure to dress warm (it is winter out there!) and make a point to count and record your observations. Meteor shower observing is one of the few remaining scientific endeavors that remains low tech. Also, don’t forget to participate in the #meteorwatch via Twitter! This shower has a broad peak, and will be active the week of December 12th until the 18th, when the solstice-centered Ursids become active. In fact, there are some indications that the Geminids have been increasing in activity over the past decade, and certainly there’s a lot of material out there. The predicted peak centers on 5:00 AM UTC, just past midnite Tuesday morning from the US East Coast. And if that weren’t enough, it’s one of the last meteor showers with the Moon placed below the horizon until 2012; only the Quadrantids and Giacobinids have the same favorable geometry in 2011. Good luck, and be sure not to miss this unique meteor shower!         

The astro-term for this week is the Yarkovsky Effect. The parent body that produces the Geminids, 3200 Phaethon, harbors somewhat of a mystery. Discovered in 1983, this space rock has been identified as the source of the Geminid meteor stream.NASA researchers estimate a massive amount of material exists, more than 100 times that of the average meteor stream. Unlike most streams that emanate from comets, however, 3200 Phaethon is an asteroid. Or is it an inactive comet? The mystery deepens, as the color of this strange rock is very similar to another asteroid, Pallas. 3200 Phaeton’s path sees it passing within Mercury’s orbit every 1.4 years, which brings it well within the realm of the Yarkovsky effect. This is the tiny bit of momentum imparted on a rotating body as it re-radiates photons absorbed from the Sun. On large bodies the effect may be negligible, but on tiny asteroids it can produce major changes in orbit over time. In fact, employing the Yarkovsky Effect by changing the reflectivity of an Earth-crossing asteroid is one way of possibly deflecting a lethal space rock. Is 3200 Phaethon a dormant comet or the remnant of an asteroid belt break up? This is one worldlet that definitely begs future exploration.      

The final meteor shower of 2010 is the Geminids, the peak of which falls on the night of the 13/14 December 2010. The Geminids is described by the IMO as “one of the finest, and probably the most reliable, of the major annual showers presently observable”, and this year’s shower is set to put on a good show. (You can read the IMO’s rather technical summary of the 2010 Geminids here: http://www.imo.net/calendar/2010#gem)

It won't look like this

The predicted Zenith Hourly Rate (see my previous post about ZHR and what it actually means here) is around 120. Although the peak is predicted to occur around 1100 on 14 December, it should happen some time between 1840 on 13 December and 1600 on 14 December 2010. The best time for the peak to occur for stargazers in the UK would be between 0030 and 0600 on 14 December, after the Moon sets but before twilight begins.

The radiant for this shower is actually quite favourable, and if you wait till the Moon sets at around 0030 on 14 December then the only light pollution limiting your view will be man-made. If you observe before the Moon sets then you will lose a few of the fainter Geminids in its glow, but it’s only a first quarter moon, and so will only really have an impact if you’re observing from very dark skies.

Let’s use the equation relating ZHR to actual observations of meteors to work out how many you might see:

Actual Hourly Rate = (ZHR x sin(h))/((1/(1-k)) x 2^(6.5-m)) where

h = the height of the radiant above the horizon

k = fraction of the sky covered in cloud

m = limiting magnitude

In the case of the 2010 Geminids, if observed from the UK, h = 45 degrees. Let’s assume you have clear skies (haha) with k = 0.

The number of Geminids you can expect to see from a variety of observing sites is as follows:

For very light polluted sites, such as city centres m = 3, and therefore you can expect to see only around 8 meteors per hour.

In suburban skies near a city or town centre m = 4, and you’ll see around 15 meteors per hour.

In rural skies where m = 5, you’ll see 30 meteors per hour.

Under very dark skies, where m = 6.5 (i.e. where there is no or negligible effect of light pollution, like in Galloway Forest Dark Sky Park) you’ll see up to 85 meteors per hour, once the Moon sets. A first quarter moon will impose a limiting magnitude, even at a very dark site, of around 6, in which case you’ll see a slightly reduced 60 meteors per hour.

Remember, all of these numbers assume perfectly clear skies. If half your sky is cloudy, cut these numbers in half!

How many Geminid meteors will I see?

If you fancy a good view of this spectacular meteor shower, then head to Galloway Forest Dark Sky Park, where we have an evening of talks and meteorwatching planned, weather permitting!

Originally posted by Steve Owens (@darkskyman) on his blog Dark Sky Diary Pursuing darkness in an increasingly bright world

The Lion Tamer – Leonid Meteor Shower 2010

Originally posted on and full credit Universe Today

Are you ready to walk into the lion’s cage? Then break out your favorite skywatching gear because the 2010 Leonid meteor shower is underway…

In the pre-dawn hours on the mornings of November 17 and November 18, the offspring of Comet Temple/Tuttle will be flashing through our atmosphere and just taunting you to test your meteor watching skills against bright skies. Although the phat Moon will greatly interfere with fainter meteor trails, don’t let that stop you from enjoying your monring coffee with the sparkling “cubs” that will be shooting out from the constellation of Leo.

Where? For all observers the constellation of Leo is along the ecliptic plane and will be near its peak height during best viewing times. When? Because of the Moon, just a couple of hours before local dawn is the best time to watch. Why? Read on!

Although it has been a couple of years since Temple/Tuttle was at perihelion, don’t forget that meteor showers are wonderfully unpredictable and the Leonids are sure to please with fall rate of around 20 (average) per hour. Who knows what surprises it may bring! Each time the comet swings around our Sun it loses some of its material in the debris trail. Of course, we all know that is the source of a meteor shower, but what we don’t know is just how much debris was shed and where it may lay.

As our Earth passes through the dusty matter, it may encounter a place where the comet let loose with a large amount of its payload – or it may pass through an area where the “comet stuff” is thin. We might even pass through an area which produces an exciting “meteor storm” like the Leonids produced in 1883! For those in the know, the Leonid meteor shower also made a rather incredible appearance in 1866 and 1867 – dumping up to 1000 (not a typo, folks) shooting stars recorded even with a Moon present! It erupted again in 1966 and in 1998 and produced 3000 (yep. 3000!) video recorded meteors during the years of 2001 and 2002. But remember, human eyes may only be able to detect just a few…

And I ain’t lion!

Photo Courtesy of Stardate.org, Texas University

Earth is entering a broad stream of debris from Halley's Comet, and this is causing the annual Orionid meteor shower. "The best time to look is during the hours before dawn on Thursday, Oct. 21st, and again on Friday, Oct 22nd," advises Bill Cooke of NASA's Meteoroid Environment Office. "Unfortunately, we have a bright Moon this year. Even so, I'd expect some bright Orionids to shine through the moonlight." An all-sky camera at the University of Western Ontario recorded this early Orionid fireball on Oct. 18th:

Orionid meteors stream from the elbow of Orion the Hunter: sky map. Because the shower's radiant point is close to the celestial equator, sky watchers in both hemispheres can enjoy the show. Moonlit meteor rates will probably be around a dozen per hour.

Radar rates could be much higher. The US Air Force Space Surveillance Radar in Texas is scanning the skies for satellites, space junk, and meteoroids. When an Orionid passes overhead–ping!–there is an echo. Moonlight does not interfere with this method of meteor observing, so it's perfect for this year's Orionids. Tune into Spaceweather Radio for live echoes.

Orionid images: from John Chumack of Dayton, Ohio; from Calvin Hall of Knik Valley, near Palmer Alaska; from Martin Popek of Nýdek, Czech republic

Originally posted on www.spaceweather.com