Jika anda ternampak muka saya tengah TT (Teh Tarik) ni, bermakna anda telah selamat mengharungi 3 hari bumi tak jadi bergelap, dan tarikh 21hb Dis yang penuh tragis dan huru-hara (kononlah).
Nak ceritanya, Falak Online telah pun berpindah rumah. Bermula sekarang silalah kemaskini link ke WWW.FALAKONLINE.NET , tak perlulah letak apa-apa selepas tu, kerana ia akan redirect ke muka hadapan BARU yang sepatutnya.
Laman lama (yang anda lihat sekarang ni), InsyaAllah akan kekal untuk beberapa bulan mendatang. Ia akan menyenaraikan KESEMUA artikel lama saya di FO, bagi rujukan anda semua. Maka, kalau anda nak masih nak marah-marah kat saya berkenaan artikel "3 hari bergelap tu" , masih boleh berbuat demikian, saya terima dengan hati terbuka! :-)
Apa pun, InsyaAllah 2013 mendatang akan terdapat beberapa pembaharuan yang saya dan rakan-rakan Personaliti Astronomi lain usahakan, demi kemajuan bidang Astronomi di Malaysia.
Jom dan Selamat Datang Ke Tahun Baru 2013.
Jemput masuk ---> WWW.FALAKONLINE.NET
As the evening sky wheels around in late autumn, a mythic drama plays out in the stars above. Taking center stage, almost directly overhead at nightfall, is Cassiopeia, the Queen.
During November, skygazers at mid-northern latitudes have front-row seats to one of the great dramas of Roman mythology. The royal family of boastful Cassiopeia and her husband Cepheus soar high overhead. Nearby is their daughter Andromeda, chained to a rock and seemingly doomed. But Perseus, the hero of this saga, swoops in to save her.
Follow these constellations throughout the night as they wheel around Polaris, the North Star. Also high up is Pegasus, the Winged Horse, easily recognized by the Great Square of stars that mark its upper body.
Meanwhile, the only planet visible immediately after sunset is Mars, lurking very low in the southwest. Venus and Saturn are both lost in the Sun's glare. If you are up around midnight, watch for Jupiter rising in the east.
Arriving around mid-month, right on schedule, is the Leonid meteor shower, so called because the streaks of these shooting stars appear to radiate from the constellation Leo. Normally it’s a pretty modest display best seen before dawn on the 17th and 18th.
You can get a personal tour of the stars and constellations overhead on November evenings by downloading the 6-minute-long stargazing podcast below.
There's no better guide to what's going on in nighttime sky than the November issue of Sky & Telescope magazine.
For Halloween, the first-quarter Moon shines in the south after dark. It's between Altair, very high to its upper right, and Fomalhaut, far down to its lower left.
Saturday, November 1
As the stars come out, Deneb is nearly straight overhead as seen from mid-northern latitudes. Brighter Vega is west of the zenith. Altair is farther from the zenith toward the south.
Sunday, November 2
Algol should be at its minimum light, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 10:07 p.m. EST (7:07 p.m. PST). Its fading and rebrightening take several additional hours before and after. Here's a comparison-star chart giving the magnitudes of three stars near Algol; use them to judge its changing brightness.
Monday, November 3
As autumn proceeds, the Great Square of Pegasus looms ever higher at nightfall. It now reaches its level position very high toward the south as early as 8 or 9 p.m. this week — with the Moon shining under its left side tonight (for North America).
Tuesday, November 4
As the stars come out, look high above the waxing gibbous Moon for the Great Square of Pegasus. It's standing on one corner.
Wednesday, November 5
Algol is at minimum light for a couple hours centered on 6:56 p.m. EST.
Thursday, November 6
Full Moon (exactly full at 5:23 p.m. Eastern Standard Time). The Moon shines far below the two or three brightest stars of Aries during the evening. Can you see the Pleiades through the moonlight? The delicate little cluster is well to the Moon's left.
Friday, November 7
The Moon, just past full, rises in the east at dusk. Once it climbs high, look for orange Aldebaran to its lower left and the Pleiades to its upper left.
Saturday, November 8
The waning gibbous Moon rises around the end of twilight. Look for Aldebaran not very far to its upper left. Higher above Aldebaran are the Pleiades.
Want to become a better astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.
This is an outdoor nature hobby; for an easy-to-use constellation guide covering the whole evening sky, use the big monthly map in the center of each issue of Sky & Telescope, the essential guide to astronomy. Or download our free Getting Started in Astronomy booklet (which only has bimonthly maps).
Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The standards are the little Pocket Sky Atlas, which shows stars to magnitude 7.6; the larger and deeper Sky Atlas 2000.0 (stars to magnitude 8.5); and once you know your way around, the even larger Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope.
You'll also want a good deep-sky guidebook, such as Sue French's Deep-Sky Wonders collection (which includes its own charts), Sky Atlas 2000.0 Companion by Strong and Sinnott, the bigger Night Sky Observer's Guide by Kepple and Sanner, or the beloved if dated Burnham's Celestial Handbook.
Can a computerized telescope replace charts? Not for beginners, I don't think, and not on mounts and tripods that are less than top-quality mechanically (able to point with better than 0.2° repeatability, which means fairly heavy and expensive). As Terence Dickinson and Alan Dyer say in their Backyard Astronomer's Guide, "A full appreciation of the universe cannot come without developing the skills to find things in the sky and understanding how the sky works. This knowledge comes only by spending time under the stars with star maps in hand."-->
Mercury is having its best dawn apparition of 2014 for skywatchers at mid-northern latitudes. It hangs low above the eastern horizon in mid-dawn, brightening slightly from magnitude –0.6 to –0.8 this week. Fainter Spica glimmers nearby. Don't confuse Mercury with Arcturus well off to the left in the east-northeast. See our article, Where, When, and How to See Mercury.
Venus is hidden the glare of the Sun.
Mars (magnitude +0.9) remains in the southwest as twilight fades. Look for it very far below Altair.
Jupiter (magnitude –2.0, between Cancer and Leo) rises in the east-northeast around midnight standard time. By dawn it shines high in the south, with Regulus nearly a fist-width lower left of it.
Saturn is lost in the sunset.
Uranus (magnitude 5.7, in Pisces) and Neptune (magnitude 7.9, in Aquarius) are high in the southeast and south, respectively, shortly after dark now. See our finder charts for Uranus and Neptune online or in the September Sky & Telescope, page 50.
All descriptions that relate to your horizon — including the words up, down, right, and left — are written for the world's mid-northern latitudes. Descriptions that also depend on longitude (mainly Moon positions) are for North America.
Eastern Daylight Time (EDT) is Universal Time (UT, UTC, or GMT) minus 4 hours. Eastern Standard Time (EST) is UT minus 5 hours.
“This adventure is made possible by generations of searchers strictly adhering to a simple set of rules. Test ideas by experiments and observations. Build on those ideas that pass the test. Reject the ones that fail. Follow the evidence wherever it leads, and question everything. Accept these terms, and the cosmos is yours.”
— Neil deGrasse Tyson, 2014.
Astronomers are peering into a galaxy cluster’s past, using Hubble’s Frontier Fields to measure the light from ghost stars cast adrift in galaxy collisions.
Imagine you’re on a faraway planet where night skies are bereft of the thousands of stars we’re accustomed to on Earth. Instead, skies are dark but for the hazy wisps of dozens or even hundreds of nearby galaxies.
That’s the night sky you might see if you're orbiting a ghost star, long since pulled free from its host galaxy during a galactic encounter. In a crowded cluster like Abell 2744, a galaxy has a good chance of experiencing a glancing collision, merger, or full-on disruption. Cast adrift in intergalactic space, the remnant stars emit a faint glow known as intracluster light, and until now, it has remained mostly a subject of theory.
The Hubble Space Telescope’s Frontier Fields, a multiyear undertaking to map six faraway galaxy clusters in exquisite detail, is changing that. The first to be imaged is Abell 2744, a cluster that had already earned the nickname Pandora’s Cluster for its violent past. It is the site of a near-simultaneous pile-up of four smaller clusters. Light from its hundreds of galaxies has traveled 3.5 billion years to reach Earth.
Now Mireia Montes and Ignacio Trujillo (University of La Laguna, Spain) have used Hubble’s long stare to construct visible-light and near-infrared color images of the cluster. They split these color images by brightness, so that they can examine the color not just of the luminous galaxies but also of the much fainter intracluster light.
“The authors say that the intracluster light is a not-well defined quantity, observationally speaking,” says theorist Emanuele Contini (University of Trieste, Italy). “I would say that observers do not have many other choices!” While theorists can track every star as they model a galaxy cluster’s evolution, observational astronomers must define intracluster light as any light below some threshold in surface brightness.
Given the incredibly faint threshold, few telescopes are capable of saying much about intracluster light other than that it exists. But in these Hubble observations, Montes and Trujillo can use the color of the cluster’s faintest glow to reveal the ghost stars’ age.
Compared to stars contained with the cluster’s galaxies, the ghost stars emit bluer light, implying a higher metal content. (Astronomers have an odd habit of defining metals as anything not hydrogen or helium. Generally, the more metals a star contains, the younger it is.) The ghost stars appear to be on average between 3 and 9 billion years younger than the stars within the cluster's galaxies, closer in age and metallicity to stars within a Milky Way-size galaxy.
When Montes and Trujillo calculate the total mass emitting the "ghost light", they find it's 6% or so of the cluster’s total stellar mass. In other words, more than a hundred billion Suns’ worth of stars are floating around between the cluster’s galaxies.
Knowing the mass and age of the cluster's ghost light, the authors propose a simplest-case scenario: sometime relatively recently in this cluster’s history, violent collisions tore apart between four and six Milky Way-size galaxies, scattering their stars into intergalactic space. Contini notes that this is undoubtedly a lower limit, since any given galaxy collision is more likely to strip some stars rather than utterly destroy the galaxy.
Montes and Trujillo plan similar studies to piece together the collision history for the Fronter Fields’ other five galaxy clusters. The duo will also expand their study of Abell 2744 to include Hubble’s ultraviolet observations, which can pin down the ghost stars’ ages with even higher precision, a step theorists and observational astronomers alike agree is necessary to understanding galaxy clusters’ violent pasts.
M. Montes & I. Trujillo. "Intracluster Light at the Frontier: A2744." Astrophysical Journal. October 20, 2014.
Learn more about what the Frontier Fields have in store for us in our January 2015 issue - subscribe now!
The innermost planet is well known for its speedy motion around the Sun, but you can spot it early in November hovering over the eastern horizon before sunrise.
In Roman mythology, Mercury is the fleet-footed messenger of the gods. His planetary namesake is equally famous for quick movement. The innermost planet zips around the Sun in just 88 days. This orbital pep, combined with the planet's closeness to the Sun, gives Mercury a reputation of being difficult to spot in the sky.
But, really, it's not hard to see Mercury — and this coming week you'll have a chance to prove it to yourself.
Mercury is in the midst of its best morning appearance of the year. It's been rapidly climbing in the predawn twilight, and on November 1st its elongation (angular separation) from the Sun maxes at 18.7°.
That's not particularly favorable; the planet's greatest elongation can reach 28° at times. However, thanks to a favorable tilt of the ecliptic during northern autumn, these crisp mornings the planet is perched almost directly above the Sun.How To See Mercury in November
As the month begins, Mercury rises about 90 minutes before the Sun, and it climbs to about 10° above the horizon as twilight starts to brighten. (Your clenched fist, held at arm's length, covers roughly 10° of sky.) So find a spot with a clear, unobstructed view toward east, and then head out about an hour before dawn. Skygazers in the U.S. will be adjusting clocks on November 2nd, as we return to standard time; after that aim to be outside no later than about 5:30 a.m.
Mercury shines at magnitude –0.6 on November 1st, so it will be fairly easy to spot. Also look for the star Spica, fainter at 1st magnitude, a few degrees to the planet's lower right. As the days pass, Spica will climb higher and Mercury will slip — by November 8th their roles have reversed, with Spica higher up.
The planet brightens throughout November, as it rounds the Sun and becomes more fully illuminated from Earth's perspective. But dawn's twilight outpaces and soon overwhelms that modest gain. So plan to spot Mercury while you can — by eye during the next two weeks and using binoculars during the week afterward.
Add a comment below (especially if your a Mercury "first-timer") to let me know about your efforts to spot this elusive celestial target.
Want to hold the innermost planet in your hands? Check out Sky & Telescope's new, highly detailed Mercury globe.
Senior contributing editor Bob Naeye recently led a Sky & Telescope tour of Iceland, where 50 astro-tourists were treated to spectacular views of the Northern Lights.
A group of about 50 astro-tourists were treated to four nights of auroras during a recently concluded week-long Sky & Telescope tour of Iceland. Conducted in partnership with Spears Travel, my fellow travelers and I also enjoyed spectacular waterfalls, an active geyser, and a uniquely idyllic culture.
“My wife and I both had a great time and are already planning our return trip,” says Mike Hoffert of Garden Grove, California.
“It was a wonderful trip and it was so nice to meet you as well. This trip met all my expectations,” adds Kathy Keith of Saint John, New Brunswick.
During an S&T aurora tour of Iceland in April 2013, we didn’t see any auroras until the final two nights of our trip, and even those displays were modest at best. This time around, the Weather Gods and the Sun were more cooperative.
On our first nighttime bus ride out, Monday, October 20th, we saw multiple aurora displays from a dark mountainous site about 25 miles east of the capital city Reykjavik. Although the auroras remained pale white in color, photos taken by tour members captured vivid greens and occasional splashes of red. I was fascinated by the speed at which the auroras changed form and how quickly they would come and go. At times, the auroras were all around us, and directly overhead. Given that most of the tour group members had never seen an aurora, I felt relief knowing that the trip was already a success in most of their minds. The skies that night were nearly crystal clear, and the temperature was cold but tolerable.
We also saw several auroras the following night from a site about 25 miles north of Reykjavik. But these auroras were much weaker than those on the previous night, and the sky was mostly cloudy. We gave up around midnight and headed back to our downtown Reykjavik hotel.
Spears Travel put together a jam-packed itinerary of daytime activities but also arranged some optional tours and downtime. These activities are intended to insure a successful trip even if we don’t see any auroras. We were given a scenic tour of Reykjavik, which despite its relatively small metro area population of about 200,000, is a major cultural center with high-end museums, shops, and restaurants. The capital region contains about two-thirds of Iceland’s total population.
On Tuesday we did the famous Golden Circle tour, which includes stops at a rift valley where the North American and Eurasian tectonic plates are pulling apart (it’s also the site of the first Icelandic parliament about a millennium ago), a geothermal area with an active geyser (Strokkur), and a spectacular waterfall known as Gullfoss. This year, a beautiful rainbow seemed to hover over the falls. I found where the rainbow ended, but alas, there was no pot of gold.
On Thursday and Friday we toured the rugged south coast of Iceland, with towering cliffs, glaciers, and black-sand beaches. We briefly stopped at a farm just below the volcano Eyjafjallajökull, which despite its impossible-to-pronounce name gained worldwide notoriety in 2010 for disrupting air traffic over Europe for weeks. Other highlights included stops at two large waterfalls (Skogafoss and Seljalandsfoss) and a hike in Vatnajökull National Park.
Friendly and informative Icelandic guides served us during the entire trip. For example, our daytime guide, Elin Konrádsdóttir, told us that Iceland has prison space for only about 100 inmates, and that the maximum sentence for murder is 15 years. Despite this leniency, Iceland averages fewer than two murders per year, and the nation has very little crime, very few police, and no army or navy (but it is a member of NATO).
We saw gorgeous auroral displays on our final two nights. On Thursday, we saw rapidly changing auroras from the tiny village of Kirkjubæjarklaustur (try pronouncing that!) in south-central Iceland. The following night we were staying at a hotel near Iceland’s famous Blue Lagoon geothermal spa. Clouds were rolling in around 11 p.m., so most of us (including me) went to bed, thinking there wasn’t much chance of seeing auroras. But several folks stayed up and were treated to what they described as the best auroral display of the trip.
The following morning we packed our belongings, enjoyed a refreshing 90-minute swim in the Blue Lagoon, and then headed to Keflavik International Airport for our flights home. Like most of my previous astro-tours, the best part of this trip was meeting so many interesting and friendly people. Most of our group came from the U.S., but we had two Canadians, two South Africans, two Australians, and a couple from Malta. The group bonded extremely well, and it was difficult to part ways after spending such a pleasant week together.
Overall, this was my fourth tour of Iceland, and I saw auroras on three of these trips (so I’m batting 0.750). I have enjoyed all of my trips, but this was the most successful of all due to the mostly good weather and near-perfect itinerary. S&T and Spears Travel are already thinking about future trips to Iceland, Chile, and other destinations. We welcome you to join us!
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You might call it wishful thinking, but here's how to "see" a dozen exoplanets in the fall evening sky.
When I was a boy, I read a book that inspired a love of science, outer space, and adventure. The Wonderful Flight to the Mushroom Planet by Margaret Cameron featured two young boys, Chuck and David, who met up with the brilliant but eccentric Tyco Bass. Bass invented a special "stroboscopic polarizing filter" that allowed him to see a hidden planet named Basidium very near Earth. With his help, the boys built a spaceship, traveled there to solve a crisis, and returned safely home.
While it's unlikely Earth harbors a hidden planet, amateur astronomers of the far future may one day focus their filter-equipped telescopes on distant stars to spy planets that today require the most advanced techniques to photograph, let alone see. But we needn't walk away empty-handed in the present. Instead, we can better picture these alien worlds, if only indirectly, through acquaintance with their host stars. I'll explain in a minute.
Extrasolar or exoplanets orbit stars other than the Sun. As of October 22, 2014, we know of an astonishing 1,832 of them. 1,151 gave themselves away when transiting or orbiting in front of their host stars. Astronomers look for regularly repeating dips in the star's light — usually less than 1% — that indicate shading from a transiting planet. Knowing the distance and diameter of the star, as well as the length of time the passing object dimmed the star’s light, they can determine the planet’s size and mass.
The radial velocity method, with 559 exoplanet discoveries to its credit, is the next most popular way to snag an alien world. Here, astronomers measure the slight wobble of the host star around the planet–star center of gravity caused by the gravitational tug of an orbiting planet. As the star swings toward the observer, the light leaving it is compressed toward the blue end of the spectrum. As the star moves away, its light is stretched or shifted toward the red end of the spectrum. Measuring these small shifts leads to information about a planet's orbit and mass.
We can see six of the Sun's planets without optical aid, and the remaining two require us only to use binoculars. Though no one's seen an extrasolar planet, a small number have been photographed. As you'd expect, because of their distances and sizes, all appear as points of light. That shouldn't stop us from looking up and at least picturing them in our mind's eye, though.
A surprising number of naked-eye stars have a planetary companion(s), including 1st-magnitude Fomalhaut and three 2nd-magnitude stars — Kochab in the Little Dipper, Hamal in Aries, and Leo's Algieba. There are presently about 30 in all.
For your viewing pleasure, here are maps showing a select group of 4th-magnitude and brighter stars that are accompanied by one or more exoplanets and visible in the autumn evening sky. The table below includes a few details about each to whet your appetite.
Wishing you a wonderful flight to a hidden world!Name Mass Discovered Detection method
Use a Sky & Telescope Star Wheel to guide your journey through the autumn skies!
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