fbpx . .
Astro-Event: Don’t Miss the Geminids!

Astro-Event: Don’t Miss the Geminids!

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 13th-14th, 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 Night Sky With Binoculars Tonight

The Night Sky With Binoculars Tonight

By Twitter..@Betelgeuse10

Original post http://astronomycentral.co.uk/the-night-sky-with-binoculars-tonight


 

Thursday 25th November, 2010

Get yourself outside tonight if it’s clear, pull up a deck chair, and scan the star clusters, nebulae, and even see another galaxy with your binoculars. They are just perfect for some objects like the larger open clusters. Just aimlessly wandering along the band of the Milky Way is also very enjoyable. If you have binoculars up to 10 x 50 then they’re ideal for the job, portable, and easy to hold. Anything over this size will usually need a tripod. All the objects listed here are at their best in dark skies, ideally with the bright Moon not around.

The Moon tonight…waning gibbous 73% full, rising in NE at 7.53 pm, and setting in NW at 11.36 am (GMT) (26th)

 

The Sword of Orion, and M42

Rising in the east tonight is the impressive constellation of Orion The Hunter, a sure sign of winter. It’s a striking constellation with the unmistakable, straight line of the three stars of Orion’s belt. Now look below the belt and you’ll see Orion’s Sword. To your naked eye it looks like a line of three fuzzy stars that hang down from the belt, resembling a sword. But when you look through your binos you will see that this is actually a group of star clusters, not individual stars. Notice how the middle cluster glows, especially with averted vision. What you are looking at is the famous, and probably most photographed deep sky object ever, the Orion Nebula or M42. This object is a huge and complex region of gas clouds, around 14 light years across. This place at 1,500 light years away is a vast stellar nursery, but it’s just one small part of an even larger region of gas that spans nearly the entire constellation. New stars, solar systems in formation, and even freely floating planets have all been observed in the Orion Nebula.

Tonight the Orion Nebula rises in the east at 8.01 pm, climbs highest in the south at 1.33 am (GMT), and sets in the west after sunrise.

The Orion Nebula can even be seen with the naked eye under very good skies, it is a magnitude 4.0 object

 How long will it be around for? The Orion Nebula is in a winter constellation. So it will slowly and gradually move across the sky eventually sinking into the west by the end of March, when it will make way for the spring constellations rising in the east. 

 

The Pleiades, or Seven Sisters

Rising in the north east tonight in the constellation Taurus is the one open cluster that lots of people can name and recognise, the Seven Sisters, The Pleiades, or M45. It lies between Perseus and Orion, and to the east of Auriga. You can easily see it naked eye, as a large fuzzy patch of stars. M45 is a close open cluster at just 440 light years away, it’s one of the nearest and so appears large in the sky. The stars in the cluster are also very young at only around 150 million years, and the brightest ones you can see are also the very youngest and hottest. The “Seven Sisters” cluster actually contains up to 1,400 members.

This attractive open star cluster fits nicely into your binoculars field of view, providing a very satisfying sight especially in dark skies with the Moon absent.

Tonight the Pleiades Cluster rises in the north east at 3.14 pm, it gets to its highest point in the south at 11.24 pm (GMT), and sets in the north west after sunrise.

The Pleiades Cluster is at magnitude 1.6

 How long will it be around for? The Pleiades too will be visible in the sky with the Orion Nebula until around the end of March.  

 

The Andromeda Galaxy, M31

High in the eastern sky tonight is the famous Andromeda Galaxy, or M31. It is a huge spiral galaxy 2.5 million light years away, with up to one trillion stars, and a diameter of up to 220,000 light years…more than twice the size of our Milky Way. You can even see Andromeda naked eye as a fuzzy glow, and there are two main ways to find this island universe in the sky. One is to locate the large square of Pegasus  with its four stars marking each corner. You’ll find Pegasus to the east of Perseus, and Cassiopeia. The star at the upper left of the square is called Sirrah (or Alpheratz), look to the left of Sirrah and you’ll see three stars in a line, a dimmer star and two  bright stars. The first bright star is Mirach. Now look above Mirach and you’ll see a dimmer star, look about the same distance above again from the dimmer star, and here is located the Andromeda Galaxy (M31). Another way to find M31 it is to use the right hand V of the W of Cassiopeia and imagine a line pointing down, this V points just to the left of Andromeda.

Get your binoculars on M31 and you’ll see the bright core of the galaxy as a small fuzzy blob. But keep studying and use averted vision, and you’ll soon start to make out the fainter shape of the galaxy’s disk extending out from the core. This is an object far outside the Milky Way, an entire ”island universe”. To be seen at its best Andromeda should be observed with the bright Moon absent under dark skies, but it’s still visible even from urban areas. 

Tonight the Andromeda Galaxy is rising from in the east after dusk, it’s virtually directly overhead at 8.44 pm (GMT), and eventually sinks low in the north west before sunrise. It is circumpolar, meaning it never sets in northern latitudes.

M31 is at magnitude 3.4

How long will it be around for? The Andromeda Galaxy is actually circumpolar from northern latitudes. It is nicely high in the sky now but will gradually sink to its lowest point just above the horizon in the north in mid March, before starting its rise again.

 

The Perseus Double Cluster

This cluster is one of my favourites, it looks stunning in a telescope at low power, but binoculars also show it well. The Perseus Double Cluster, NGC 884 and NGC 869, or H and X Persei are actually two seperate open star clusters close to each other in space at around 7,000 light years away. They are only a few million years old, much younger than the Pleaides. To find it I could tell you to find this star, draw a line to that star etc, but the easiest way I have found to locate the Perseus Double is just to look for a fuzzy irregular patch in the band of the Milky Way between Cassiopeia and Perseus, (cluster marked as H+X on Perseus map). Once you see it, get your binos on it and you’ll see two very attractive open clusters of sparkling stars set against the blackness of space. There’s also a nice line of stars that curves away from the upper most cluster, when you see this line of stars you’ll know you have this popular deep sky object in your view.

Tonight you’ll see the Perseus Double Cluster rising from the north east after dark and getting very high in the sky to the east. It is circumpolar meaning it’s always above the horizon and never sets.

This open cluster is a magnitude 4.00 object

 How long will it be around for? The Perseus Double Cluster will always be above the horizon, but by April it will have moved over to the north and much lower in the sky.

 

Jupiter and its moons

Jupiter the giant of the solar system is on show right now, although it is gradually on the wane as far as size and brightness go, having passed full opposition in mid September. But the solar system’s most massive planet and its collection of four main moons can be seen in binoculars. Look to the east after it goes dark and the brightest “star” you see is Jupiter. Put your binoculars on it and although the disk of the planet is small, look carefully and you should see four tiny pinpoints of light around it. These are the moons of Jupiter, Ganymede, Callisto, Io, and Europa. Jupiter’s moon Io is the most volcanic place in the entire solar system, and Europa is covered in ice with an ocean below its frozen crust. One of those four pinpoints of light you see (Europa) has more water on it than all of Earth’s oceans put together, and could even have extraterrestrial life living there. Ganymede is the largest moon in the solar system, even bigger than Mercury, and Callisto could also have a subsurface ocean. The moons shift and change postion over mere hours, so it’s a continually changing scene.

Tonight you’ll see Jupiter quite high in the south east by night fall, it rises highest in the south at 7.33 pm, and sets in the west at 1.08 am. (GMT)

Tonight Jupiter is at magnitude -2.44

How long will it be around for? Jupiter will eventually go out of sight in the setting Sun’s glow by March 2011.

 

The Beehive Cluster, M44

The Beehive Cluster, Praesepe, M44, or NGC 2632 is a very nice and attractive open star cluster to look at through your binoculars, and does kind of look like a swarm of bees. The Beehive is another open cluster close to Earth, at 577 light years away in the constellation of Cancer. This puts it slightly further away than the Pleaides. M44 rises from the north east, and you’ll see it with your naked eye as a nebulous patch on clear moonless nights. This cluster lies in the fainter constellation of Cancer, in between Leo, and Gemini. The stars that make up the head of Leo the Lion look like a large backwards question mark. You’ll find M44 with your naked eye roughly half way between this “question mark”, and the two twin stars of Castor and pollux in Gemini. The Beehive actually has over 1,000 stars, and is around 600 million years old.

This is really one for the early hours at the moment, as you’ll have to wait until beyond midnight if you want to get a good view of the Beehive Cluster. Tonight it rises from the north east at 8.41 pm (GMT), and climbs to its highest point in the south just before sunrise. Viewing this object gets more convenient in the coming weeks though, as it gradually rises earlier.

This object is at magnitude 3.7

How long will it be around for By April when M42 and the Pleiades will be sinking into the western horizon, the Beehive Cluster will still be nice and high in the sky in the south. But by June it will have disappeared below the north west horizon by nightfall.  

 

The Hyades Cluster

Look to the eastern sky, to the lower left of the Pleaides Cluster, and you’ll see the bright orange star Alderbaran. Alderbaran is an orange giant, and marks the eye of the bull in the constellation Taurus. Alderbaran marks the position of the closest star cluster to Earth, the Hyades. This star grouping of up to 400 members is large and loose, due to its closeness at a mere 151 light years away. This open cluster is so spread out that even your binoculars will just about get all of its stars in their field of view. But this is a really nice collection of suns to gaze at through your binos on crisp dark nights. It contrasts well with bright Alderbaran, although this orange giant is not actually a member of the Hyades Cluster, being much closer to Earth at 65 light years away.

Tonight the Hyades Cluster rises from the east at 4.44 pm, and gets nice and high in the south at 12.38 am (GMT), eventually sinking towards the western horizon before daybreak.

How long will it be around for? The Hyades Cluster will be on view until March/April. At this time it will be close behind the setting Sun, following it into the western horizon.   

…also check out Planets To See In The Sky Tonight

Geminids Meteor Shower 2010: What You Might See

Geminids Meteor Shower 2010: What You Might See

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?

Where are you observing from? Limiting magnitude Number of Geminids per hour
A very light polluted city centre 3 7 or 8
Suburban Site 4 15
Rural Site 5 30
Dark Sky Site 6.5 85 (after the Moon sets at 0030)

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 Leonid Meteor Shower 2010

The Leonid Meteor Shower 2010

 

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

The Orionid Meteor Shower 2010

The Orionid Meteor Shower 2010

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

Fun Facts About the Perseids!

The Perseid meteor shower is named for the constellation Perseus, from where the meteors appear to originate. The Perseid meteor shower is one of the most prolific showers of the year, with an average peak rate of 50- 80 streaks per hour, in darker skies. Meteors are the visible paths of vaporizing space debris as it encounters our planet’s atmosphere.

This debris, known as meteoroids, ranges in size from dust particles to small pebbles, and occasionally larger stones. As a meteoroid enters the Earth’s atmosphere, it is heated by friction, which vaporizes the debris and causes the gases (both atmospheric and meteoritic) to glow. Most meteoroids disintegrate at about 30-60 miles above the surface, but become visible at about 40-75 miles.

Meteoroids orbit the Sun just like planets, comets, and asteroids. They travel at speeds of about 26 mps, but, when combined with Earth’s orbital speed of about 18 mps, enter our atmosphere at a velocity rate of about 44 mps. The meteoroids associated with the Perseid meteor shower enter the Earth’s atmosphere at about 37 mps. Our planet encounters space debris every day, thus meteors are actually visible all year long.

Occasionally, Earth passes through thicker patches of debris, known as streams or swarms, resulting in a meteor “shower.” Meteoroid streams, or swarms, have orbits similar to those of comets, thus are believed to be fields of comet debris resulting from a comet’s closing approach of the Sun.

The Perseid meteor shower has been associated with the ancient debris field of Comet 109/Swift-Tuttle. Comet Swift-Tuttle leaves new debris each time it passes our planet – every 130 years. This debris field has the appearance of several streams, each measuring millions of miles long.

The Swift-Tuttle debris streams are comprised of small widely-spaced particles. Most of the meteoroids are about the size of sand grains, but some may be as large as small pebbles. With a core diameter of about 26km, comet Swift-Tuttle is the largest known object, and one of the oldest comets, to regularly pass closely to our planet.

Comet Swift-Tuttle was originally recorded by Chinese astronomers in 69 BC and 188AD, but was formally discovered in 1862, by Lewis Swift on July 16, and by Horace Parnell Tuttle on July 19. Three others also independently discovered this comet: Dudley Observatory’s Thomas Simons; Antonio Pacinotti and Carlo Toussaint from Florence, Italy; and Danish Astronomer Hans Schjellerup. Comet Swift-Tuttle was “rediscovered” in 1992 by Tsuruhiko Kiuchi, ten years after its expected return of 1982.

That year, the comet reached 5th magnitude, making it easily visible through binoculars. Comet Swift-Tuttle will pass within 14-million-miles of our planet when it next returns in 2126. Scientists believe that the comet will be even brighter than the 1992 pass, and likely readily visible to even unaided eyes.

Astronomers once believed that comet Swift-Tuttle might, in the relatively near future, pass close enough to actually impact Earth or the Moon. While continued observations and recalculations have dispelled that concern for at least the next 2,000 years, this comet remains one of the greatest known solar system threats to our planet.

Source Material: NASA Worldbook JPL’s Solar System Dynamics Gary Kronk’s Cometography Astronomical Society of the Pacific Space.com Wikipedia

By Tavi Greiner. See more from Tavi at her site A Sky Full of Stars and follow her on Twitter @TaviGreiner

Pin It on Pinterest