August 20, 2010
Antares: Heart of the Scorpion
On summer evenings, you can spot red Antares, the ruby Heart of Scorpius the Scorpion. It is the 16th brightest star and one of the most gigantic stars known.
Bright reddish Antares – also known as Alpha Scorpii – is easy to spot on a summer night. It is the brightest star – and distinctly reddish in color – in the fishhook-shaped pattern of stars known as the constellation Scorpius the Scorpion.
If you look southward in early evening from late spring to early fall, you’re likely to notice this fishhook pattern, with ruby Antares as its heart. If you think you’ve found Antares, aim binoculars in its direction. You should notice its reddish color. And you should see a little star cluster – known as M4 – just to the right of this star.
Bright reddish Antares – also known as Alpha Scorpii – is easy to spot on a summer night. It is the brightest star – and distinctly reddish in color – in the fishhook-shaped pattern of stars known as the constellation Scorpius the Scorpion.
If you look southward in early evening from late spring to early fall, you’re likely to notice this fishhook pattern, with ruby Antares as its heart. If you think you’ve found Antares, aim binoculars in its direction. You should notice its reddish color. And you should see a little star cluster – known as M4 – just to the right of this star.
August 10, 2010
An Evening Dance of Planets
Step outside as evening twilight fades, and from now through the middle of August you’ll find three planets shining low in the west — one much brighter than the other two. Venus will leap out at you, but you may need to wait for the sky to darken a bit more before fainter Saturn and Mars glimmer into view.
Saturn and Mars are five magnitudes fainter than Venus and thus only about 1% as bright. They're side by side in the sky, separately by three or four fingers held together at arm’s length. They'll spend the coming week sliding to the right with respect to Venus, creating a planetary triangle that changes shape from day to day. The crescent Moon joins the twilight planet scene on Thursday, August 12th (when it’s below Venus), and on Friday, the 13th (when it’s left of Venus).
Saturn and Mars are five magnitudes fainter than Venus and thus only about 1% as bright. They're side by side in the sky, separately by three or four fingers held together at arm’s length. They'll spend the coming week sliding to the right with respect to Venus, creating a planetary triangle that changes shape from day to day. The crescent Moon joins the twilight planet scene on Thursday, August 12th (when it’s below Venus), and on Friday, the 13th (when it’s left of Venus).
August 9, 2010
Tips for watching meteors
The 2010 Perseid meteor shower – August’s famous ’shooting stars’ – will peak in this coming week, on the mornings of August 12 and 13. The shower has been gradually rising to a peak since early August. Any night this week, you might see Perseid meteors.
Here are a few tips to help you get the most out of the show.
Most important: a dark sky. Here’s the first thing – the main thing – you need to know to become as proficient as the experts at watching meteors. That is, to watch meteors, you need a dark sky.
Know your dates and times. You also need to be looking on the right date, at the right time of night. For the Perseids, the best time is midnight to dawn on the mornings of August 12 and 13. But you might also see Perseids before those dates, since the shower builds to a peak gradually. Afterward, it falls off rapidly. The nights before the Perseid’s peak are probably better for meteor-watching than the nights afterward. Meteor showers occur over a range of dates, because they stem from Earth’s own movement through space. As we orbit the sun, we cross “meteor streams.” These streams of icy particles in space come from comets moving in orbit around the sun. Comets are fragile icy bodies that litter their orbits with debris. When this cometary debris enters our atmosphere, it vaporizes due to friction with the air. If moonlight or city lights don’t obscure the view, we on Earth see the falling, vaporizing particles as meteors.
What to bring. You can comfortably watch meteors from many places, assuming you have a dark sky: your back yard or deck, the hood of your car, the side of a road. If you want to bring along equipment to make you more comfortable, consider a blanket or reclining lawn chair, a thermos with a hot drink, binoculars for gazing along the pathway of the summer Milky Way. Be sure to dress warmly enough. Even the summer nights can be chilly, especially in the hours before dawn when most meteors should be flying.
Are the predictions reliable? Although astronomers have tried to publish exact predictions in recent years, meteor showers remain notoriously unpredictable. Your best bet is to go outside at the times we suggest, and plan to spend at least an hour reclining comfortably while looking up at the sky.
Rami B.
Here are a few tips to help you get the most out of the show.
Most important: a dark sky. Here’s the first thing – the main thing – you need to know to become as proficient as the experts at watching meteors. That is, to watch meteors, you need a dark sky.
Know your dates and times. You also need to be looking on the right date, at the right time of night. For the Perseids, the best time is midnight to dawn on the mornings of August 12 and 13. But you might also see Perseids before those dates, since the shower builds to a peak gradually. Afterward, it falls off rapidly. The nights before the Perseid’s peak are probably better for meteor-watching than the nights afterward. Meteor showers occur over a range of dates, because they stem from Earth’s own movement through space. As we orbit the sun, we cross “meteor streams.” These streams of icy particles in space come from comets moving in orbit around the sun. Comets are fragile icy bodies that litter their orbits with debris. When this cometary debris enters our atmosphere, it vaporizes due to friction with the air. If moonlight or city lights don’t obscure the view, we on Earth see the falling, vaporizing particles as meteors.
What to bring. You can comfortably watch meteors from many places, assuming you have a dark sky: your back yard or deck, the hood of your car, the side of a road. If you want to bring along equipment to make you more comfortable, consider a blanket or reclining lawn chair, a thermos with a hot drink, binoculars for gazing along the pathway of the summer Milky Way. Be sure to dress warmly enough. Even the summer nights can be chilly, especially in the hours before dawn when most meteors should be flying.
Are the predictions reliable? Although astronomers have tried to publish exact predictions in recent years, meteor showers remain notoriously unpredictable. Your best bet is to go outside at the times we suggest, and plan to spend at least an hour reclining comfortably while looking up at the sky.
Rami B.
August 4, 2010
Dark Nights for the Perseids
The last time the annual Perseid meteor shower happened during a run of good moonless nights was in 2007. It turns out that every three years, the same phase of the Moon returns to roughly the same date each month (2.2 days earlier, on average). So in 2010 we're on for moonless Perseids again!
The shower lasts for many days, but according to the International Meteor Organization this year's peak should occur during a half-day-long window centered on 1:00 Universal Time on August 13th, which is ideal timing for skywatchers in Eurasia. For North Americans, the best viewing will probably be late Thursday night and early Friday morning, August 12-13, or possibly the night before.
The shower lasts for many days, but according to the International Meteor Organization this year's peak should occur during a half-day-long window centered on 1:00 Universal Time on August 13th, which is ideal timing for skywatchers in Eurasia. For North Americans, the best viewing will probably be late Thursday night and early Friday morning, August 12-13, or possibly the night before.
July 31, 2010
Summer Meteor Shower Season in Full Swing
For skywatchers in the Northern Hemisphere, late summer is usually regarded as the prime "meteor-viewing season," with one of the best displays of the year reaching its peak in mid-August. But some lesser-known summer meteor displays can still dazzle.
The summer meteor shower season hits its peak with the annual Perseid meteor shower, which is usually beloved by everyone from meteor enthusiasts to summer campers in August. This year will be an excellent one for the Perseids, as their peak will nearly coincide with a new moon, which should offer dark skies for prospective observers.
But the Perseids aren't the only meteor show in town.
The summer meteor shower season hits its peak with the annual Perseid meteor shower, which is usually beloved by everyone from meteor enthusiasts to summer campers in August. This year will be an excellent one for the Perseids, as their peak will nearly coincide with a new moon, which should offer dark skies for prospective observers.
But the Perseids aren't the only meteor show in town.
July 25, 2010
How to Measure Distances in the Night Sky
Sometimes, the apparent distance between two celestial objects – the distance we can actually see on the sky – is indicated in terms of angular degrees. But these descriptions can seem like a foreign language to folks who don't pore over star charts every day, so here's a handy primer.
If we measured the distance around the circle of the entire horizon – from north all the way around through east and south and west and back to north again – that would equal 360-degrees.
From the horizon to the point directly overhead (the zenith) would equal 90-degrees; from one horizon point through the zenith and continuing across to the opposite side of the sky would measure 180-degrees.
If we measured the distance around the circle of the entire horizon – from north all the way around through east and south and west and back to north again – that would equal 360-degrees.
From the horizon to the point directly overhead (the zenith) would equal 90-degrees; from one horizon point through the zenith and continuing across to the opposite side of the sky would measure 180-degrees.
July 19, 2010
Total solar eclipse from Lebanon: past and future
A few lucky astronomers and inhabitants of remote islands in the Pacific Ocean had the view of a lifetime on July 11th when a total solar eclipse graced their skies.
Of course lots of people in Lebanon and the region still remember the March 29th 2006 solar eclipse. The path of totality of the Moon's shadow began at sunrise in Brazil and extended across the Atlantic to Africa, traveling across Ghana, Togo, Benin, Nigeria, Niger, Chad, Libya, and a small corner of Egypt, from there across the Mediterranean Sea to Greece (Kastellórizo) and Turkey, then across the Black Sea via Georgia, Russia, and Kazakhstan to Western Mongolia, where it ended at sunset. A partial eclipse was seen from the much broader path of the Moon's penumbra, including the northern two-thirds of Africa, the whole of Europe, and Central Asia. In Lebanon 86.1% of the Sun's disk was obscured by the Moon. A great spectacle indeed. I still remember the hint of darkness at maximum eclipse as well as the uninvited clouds which ruined the last half hour of the eclipse!
However I didn't have to wait long for another solar eclipse. January 15th 2010: 10.3% of the Sun's disk got covered by the Moon during the chilly early morning hours. Not as spectacular as the 2006 eclipse but worth watching.
So what's next? Well using the Solar Eclipse Explorer provided by the NASA Eclipse website (http://eclipse.gsfc.nasa.gov/JSEX/JSEX-AS.html) it's easy to compute the local circumstances for every solar eclipse visible from Beirut for any century from -1499 to 3000 (1500 BCE to 3000 CE). Here's what I found:
Rami B.
For more info on solar eclipses check out the following links:
Of course lots of people in Lebanon and the region still remember the March 29th 2006 solar eclipse. The path of totality of the Moon's shadow began at sunrise in Brazil and extended across the Atlantic to Africa, traveling across Ghana, Togo, Benin, Nigeria, Niger, Chad, Libya, and a small corner of Egypt, from there across the Mediterranean Sea to Greece (Kastellórizo) and Turkey, then across the Black Sea via Georgia, Russia, and Kazakhstan to Western Mongolia, where it ended at sunset. A partial eclipse was seen from the much broader path of the Moon's penumbra, including the northern two-thirds of Africa, the whole of Europe, and Central Asia. In Lebanon 86.1% of the Sun's disk was obscured by the Moon. A great spectacle indeed. I still remember the hint of darkness at maximum eclipse as well as the uninvited clouds which ruined the last half hour of the eclipse!
However I didn't have to wait long for another solar eclipse. January 15th 2010: 10.3% of the Sun's disk got covered by the Moon during the chilly early morning hours. Not as spectacular as the 2006 eclipse but worth watching.
So what's next? Well using the Solar Eclipse Explorer provided by the NASA Eclipse website (http://eclipse.gsfc.nasa.gov/JSEX/JSEX-AS.html) it's easy to compute the local circumstances for every solar eclipse visible from Beirut for any century from -1499 to 3000 (1500 BCE to 3000 CE). Here's what I found:
- January 4th 2011: the next solar eclipse visible from Lebanon. It will be a partial eclipse, visible in the morning hours, with approximately 50% of the Sun's disk obscured at maximum eclipse.
- November 3rd 2013 and March 20th 2015: unremarkable partial solar eclipses with barely 1% of the Sun's disk covered by the Moon.
- June 21st 2020: a beautiful eclipse at sunrise with about 31% obstruction at maximum eclipse.
Rami B.
For more info on solar eclipses check out the following links:
July 10, 2010
Remote Easter Island Is Place to Be for Sunday Solar Eclipse
On Sunday July 11th, the moon will pass between the sun and the Earth and throw its dark shadow upon our planet's surface in one of nature's great spectacles: a total eclipse of the sun. It could be the ultimate cosmic photo op, but only if you're on the remote Easter Island.
July 10, 2010
Disappearing Act on Jupiter
One of the giant planet's signature bands, the South Equatorial Belt, began fading late last year. Now, for the first time since 1992, it's completely missing. Amateur and professional observers worldwide are eagerly hoping to witness its return.
July 10, 2010
Cosmic Teapot Visible In Summer Sky
One of the greatest pleasures on a warm summer evening is to sit outside and enjoy the riches of our Milky Way galaxy, with one such treasure – a cosmic teapot – making a terrific target for skywatchers this week.
To spot this humble teapot in the sky, the key is the constellation Sagittarius, the archer centaur. Eight of the brightest stars in Sagittarius form an asterism called "the teapot," which appears low on the southern horizon.
To spot this humble teapot in the sky, the key is the constellation Sagittarius, the archer centaur. Eight of the brightest stars in Sagittarius form an asterism called "the teapot," which appears low on the southern horizon.