Thursday, 15 December 2016

Astronomy Calendar of Celestial Events for Calendar Year 2017



January 3, 4 - Quadrantids Meteor Shower. The Quadrantids is an above average shower, with up to 40 meteors per hour at its peak. It is thought to be produced by dust grains left behind by an extinct comet known as 2003 EH1, which was discovered in 2003. The shower runs annually from January 1-5. It peaks this year on the night of the 3rd and morning of the 4th. The first quarter moon will set shortly after midnight leaving fairly dark skies for what could be a good show. Best viewing will be from a dark location after midnight. Meteors will radiate from the constellation Bootes, but can appear anywhere in the sky.



January 12 - Full Moon. The Moon will be located on the opposite side of the Earth as the Sun and its face will be will be fully illuminated. This phase occurs at 11:34 UTC. This full moon was known by early Native American tribes as the Full Wolf Moon because this was the time of year when hungry wolf packs howled outside their camps. This moon has also been know as the Old Moon and the Moon After Yule.

January 12 - Venus at Greatest Eastern Elongation. The planet Venus reaches greatest eastern elongation of 47.1 degrees from the Sun. This is the best time to view Venus since it will be at its highest point above the horizon in the evening sky. Look for the bright planet in the western sky after sunset. 


January 19 - Mercury at Greatest Western Elongation. The planet Mercury reaches greatest western elongation of 24.1 degrees from the Sun. This is the best time to view Mercury since it will be at its highest point above the horizon in the morning sky. Look for the planet low in the eastern sky just before sunrise.

January 28 - New Moon. The Moon will located on the same side of the Earth as the Sun and will not be visible in the night sky. This phase occurs at 00:07 UTC. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.



February 11 - Full Moon. The Moon will be located on the opposite side of the Earth as the Sun and its face will be will be fully illuminated. This phase occurs at 00:33 UTC. This full moon was known by early Native American tribes as the Full Snow Moon because the heaviest snows usually fell during this time of the year. Since hunting is difficult, this moon has also been known by some tribes as the Full Hunger Moon, since the harsh weather made hunting difficult.


February 11 - Penumbral Lunar Eclipse. A penumbral lunar eclipse occurs when the Moon passes through the Earth's partial shadow, or penumbra. During this type of eclipse the Moon will darken slightly but not completely. The eclipse will be visible throughout most of eastern South America, eastern Canada, the Atlantic Ocean, Europe, Africa, and western Asia. (NASA Map and Eclipse Information)



February 26 - New Moon. The Moon will located on the same side of the Earth as the Sun and will not be visible in the night sky. This phase occurs at 14:59 UTC. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.



February 26 - Annular Solar Eclipse. An annular solar eclipse occurs when the Moon is too far away from the Earth to completely cover the Sun. This results in a ring of light around the darkened Moon. The Sun's corona is not visible during an annular eclipse. The path of the eclipse will begin off the coast of Chile and pass through southern Chile and southern Argentina, across the southern Atlantic Ocean, and into Angola and Congo in Africa. A partial eclipse will be visible throughout parts of southern South America and southwestern Africa.
(NASA Map and Eclipse Information) (NASA Interactive Google Map)



March 12 - Full Moon. The Moon will be located on the opposite side of the Earth as the Sun and its face will be will be fully illuminated. This phase occurs at 14:54 UTC. This full moon was known by early Native American tribes as the Full Worm Moon because this was the time of year when the ground would begin to soften and the earthworms would reappear. This moon has also been known as the Full Crow Moon, the Full Crust Moon, the Full Sap Moon, and the Lenten Moon.


March 20 - March Equinox. The March equinox occurs at 10:29 UTC. The Sun will shine directly on the equator and there will be nearly equal amounts of day and night throughout the world. This is also the first day of spring (vernal equinox) in the Northern Hemisphere and the first day of fall (autumnal equinox) in the Southern Hemisphere.


March 28 - New Moon. The Moon will located on the same side of the Earth as the Sun and will not be visible in the night sky. This phase occurs at 02:58 UTC. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.


April 1 - Mercury at Greatest Eastern Elongation. The planet Mercury reaches greatest eastern elongation of 19 degrees from the Sun. This is the best time to view Mercury since it will be at its highest point above the horizon in the evening sky. Look for the planet low in the western sky just after sunset.





April 7 - Jupiter at Opposition. The giant planet will be at its closest approach to Earth and its face will be fully illuminated by the Sun. It will be brighter than any other time of the year and will be visible all night long. This is the best time to view and photograph Jupiter and its moons. A medium-sized telescope should be able to show you some of the details in Jupiter's cloud bands. A good pair of binoculars should allow you to see Jupiter's four largest moons, appearing as bright dots on either side of the planet. 


April 11 - Full Moon. The Moon will be located on the opposite side of the Earth as the Sun and its face will be will be fully illuminated. This phase occurs at 06:08 UTC. This full moon was known by early Native American tribes as the Full Pink Moon because it marked the appearance of the moss pink, or wild ground phlox, which is one of the first spring flowers. This moon has also been known as the Sprouting Grass Moon, the Growing Moon, and the Egg Moon. Many coastal tribes called it the Full Fish Moon because this was the time that the shad swam upstream to spawn.


April 22, 23 - Lyrids Meteor Shower. The Lyrids is an average shower, usually producing about 20 meteors per hour at its peak. It is produced by dust particles left behind by comet C/1861 G1 Thatcher, which was discovered in 1861. The shower runs annually from April 16-25. It peaks this year on the night of the night of the 22nd and morning of the 23rd. These meteors can sometimes produce bright dust trails that last for several seconds. The crescent moon should not be too much of a problem this year. Skies should still be dark enough for a good show. Best viewing will be from a dark location after midnight. Meteors will radiate from the constellation Lyra, but can appear anywhere in the sky.



April 26 - New Moon. The Moon will located on the same side of the Earth as the Sun and will not be visible in the night sky. This phase occurs at 12:17 UTC. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.


May 6, 7 - Eta Aquarids Meteor Shower. The Eta Aquarids is an above average shower, capable of producing up to 60 meteors per hour at its peak. Most of the activity is seen in the Southern Hemisphere. In the Northern Hemisphere, the rate can reach about 30 meteors per hour. It is produced by dust particles left behind by comet Halley, which has known and observed since ancient times. The shower runs annually from April 19 to May 28. It peaks this year on the night of May 6 and the morning of the May 7. The waxing gibbous moon will block out many of the fainter meteors this year. But if you are patient, you should be able to catch quite a few of the brighter ones. Best viewing will be from a dark location after midnight. Meteors will radiate from the constellation Aquarius, but can appear anywhere in the sky.


May 10 - Full Moon. The Moon will be located on the opposite side of the Earth as the Sun and its face will be will be fully illuminated. This phase occurs at 21:42 UTC. This full moon was known by early Native American tribes as the Full Flower Moon because this was the time of year when spring flowers appeared in abundance. This moon has also been known as the Full Corn Planting Moon and the Milk Moon.


May 17 - Mercury at Greatest Western Elongation. The planet Mercury reaches greatest western elongation of 25.8 degrees from the Sun. This is the best time to view Mercury since it will be at its highest point above the horizon in the morning sky. Look for the planet low in the eastern sky just before sunrise.


May 25 - New Moon. The Moon will located on the same side of the Earth as the Sun and will not be visible in the night sky. This phase occurs at 19:45 UTC. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.


June 3 - Venus at Greatest Western Elongation. The planet Venus reaches greatest eastern elongation of 45.9 degrees from the Sun. This is the best time to view Venus since it will be at its highest point above the horizon in the morning sky. Look for the bright planet in the eastern sky before sunrise.


·  June 9 - Full Moon. The Moon will be located on the opposite side of the Earth as the Sun and its face will be will be fully illuminated. This phase occurs at 13:10 UTC. This full moon was known by early Native American tribes as the Full Strawberry Moon because it signaled the time of year to gather ripening fruit. It also coincides with the peak of the strawberry harvesting season. This moon has also been known as the Full Rose Moon and the Full Honey Moon.


·  June 15 - Saturn at Opposition. The ringed planet will be at its closest approach to Earth and its face will be fully illuminated by the Sun. It will be brighter than any other time of the year and will be visible all night long. This is the best time to view and photograph Saturn and its moons. A medium-sized or larger telescope will allow you to see Saturn's rings and a few of its brightest moons.


·  June 21 - June Solstice. The June solstice occurs at 04:24 UTC. The North Pole of the earth will be tilted toward the Sun, which will have reached its northernmost position in the sky and will be directly over the Tropic of Cancer at 23.44 degrees north latitude. This is the first day of summer (summer solstice) in the Northern Hemisphere and the first day of winter (winter solstice) in the Southern Hemisphere.


·  June 24 - New Moon. The Moon will located on the same side of the Earth as the Sun and will not be visible in the night sky. This phase occurs at 02:31 UTC. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.


·  July 9 - Full Moon. The Moon will be located on the opposite side of the Earth as the Sun and its face will be will be fully illuminated. This phase occurs at 04:07 UTC. This full moon was known by early Native American tribes as the Full Buck Moon because the male buck deer would begin to grow their new antlers at this time of year. This moon has also been known as the Full Thunder Moon and the Full Hay Moon.


·  July 23 - New Moon. The Moon will located on the same side of the Earth as the Sun and will not be visible in the night sky. This phase occurs at 09:46 UTC. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.


·  July 28, 29 - Delta Aquarids Meteor Shower. The Delta Aquarids is an average shower that can produce up to 20 meteors per hour at its peak. It is produced by debris left behind by comets Marsden and Kracht. The shower runs annually from July 12 to August 23. It peaks this year on the night of July 28 and morning of July 29. The crescent moon will set by midnight, leaving dark skies for what should be a good early morning show. Best viewing will be from a dark location after midnight. Meteors will radiate from the constellation Aquarius, but can appear anywhere in the sky.


·  July 30 - Mercury at Greatest Eastern Elongation. The planet Mercury reaches greatest eastern elongation of 27.2 degrees from the Sun. This is the best time to view Mercury since it will be at its highest point above the horizon in the evening sky. Look for the planet low in the western sky just after sunset.


·  August 7 - Full Moon. The Moon will be located on the opposite side of the Earth as the Sun and its face will be will be fully illuminated. This phase occurs at 18:11 UTC. This full moon was known by early Native American tribes as the Full Sturgeon Moon because the large sturgeon fish of the Great Lakes and other major lakes were more easily caught at this time of year. This moon has also been known as the Green Corn Moon and the Grain Moon.


·  August 7 - Partial Lunar Eclipse. A partial lunar eclipse occurs when the Moon passes through the Earth's partial shadow, or penumbra, and only a portion of it passes through the darkest shadow, or umbra. During this type of eclipse a part of the Moon will darken as it moves through the Earth's shadow. The eclipse will be visible throughout most of eastern Africa, central Asia, the Indian Ocean, and Australia. (NASA Map and Eclipse Information)


·  August 12, 13 - Perseids Meteor Shower. The Perseids is one of the best meteor showers to observe, producing up to 60 meteors per hour at its peak. It is produced by comet Swift-Tuttle, which was discovered in 1862. The Perseids are famous for producing a large number of bright meteors. The shower runs annually from July 17 to August 24. It peaks this year on the night of August 12 and the morning of August 13. The waning gibbous moon will block out many of the fainter meteors this year, but the Perseids are so bright and numerous that it should still be a good show. Best viewing will be from a dark location after midnight. Meteors will radiate from the constellation Perseus, but can appear anywhere in the sky.


·  August 21 - New Moon. The Moon will located on the same side of the Earth as the Sun and will not be visible in the night sky. This phase occurs at 18:30 UTC. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.


·  August 21 - Total Solar Eclipse. A total solar eclipse occurs when the moon completely blocks the Sun, revealing the Sun's beautiful outer atmosphere known as the corona. This is a rare, once-in-a-lifetime event for viewers in the United States. The last total solar eclipse visible in the continental United States occurred in 1979 and the next one will not take place until 2024. The path of totality will begin in the Pacific Ocean and travel through the center of the United States. The total eclipse will be visible in parts of Oregon, Idaho, Wyoming, Nebraska, Missouri, Kentucky, Tennessee, North Carolina, and South Carolina before ending in the Atlantic Ocean. A partial eclipse will be visible in most of North America and parts of northern South America. (NASA Map and Eclipse Information | Detailed Zoomable Map of Eclipse Path)


·  September 5 - Neptune at Opposition. The blue giant planet will be at its closest approach to Earth and its face will be fully illuminated by the Sun. It will be brighter than any other time of the year and will be visible all night long. This is the best time to view and photograph Neptune. Due to its extreme distance from Earth, it will only appear as a tiny blue dot in all but the most powerful telescopes.


·  September 6 - Full Moon. The Moon will be located on the opposite side of the Earth as the Sun and its face will be will be fully illuminated. This phase occurs at 07:03 UTC. This full moon was known by early Native American tribes as the Full Corn Moon because the corn is harvested around this time of year.


·  September 12 - Mercury at Greatest Western Elongation. The planet Mercury reaches greatest western elongation of 17.9 degrees from the Sun. This is the best time to view Mercury since it will be at its highest point above the horizon in the morning sky. Look for the planet low in the eastern sky just before sunrise.


·  September 20 - New Moon. The Moon will located on the same side of the Earth as the Sun and will not be visible in the night sky. This phase occurs at 05:30 UTC. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.


·  September 22 - September Equinox. The September equinox occurs at 20:02 UTC. The Sun will shine directly on the equator and there will be nearly equal amounts of day and night throughout the world. This is also the first day of fall (autumnal equinox) in the Northern Hemisphere and the first day of spring (vernal equinox) in the Southern Hemisphere.


·  October 5 - Full Moon. Moon will be directly opposite the Earth from the Sun and will be fully illuminated as seen from Earth. This phase occurs at 18:40 UTC. This full moon was known by early Native American tribes as the Full Hunters Moon because at this time of year the leaves are falling and the game is fat and ready to hunt. This moon has also been known as the Travel Moon and the Blood Moon. This moon is also known as the Harvest Moon. The Harvest Moon is the full moon that occurs closest to the September equinox each year.


·  October 7 - Draconids Meteor Shower. The Draconids is a minor meteor shower producing only about 10 meteors per hour. It is produced by dust grains left behind by comet 21P Giacobini-Zinner, which was first discovered in 1900. The Draconids is an unusual shower in that the best viewing is in the early evening instead of early morning like most other showers. The shower runs annually from October 6-10 and peaks this year on the the night of the 7th. Unfortunately, the nearly full moon will block all but the brightest meteors this year. If you are extremely patient, you may be able to catch a few good ones. Best viewing will be in the early evening from a dark location far away from city lights. Meteors will radiate from the constellation Draco, but can appear anywhere in the sky.


·  October 19 - New Moon. The Moon will located on the same side of the Earth as the Sun and will not be visible in the night sky. This phase occurs at 19:12 UTC. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.


·  October 19 - Uranus at Opposition. The blue-green planet will be at its closest approach to Earth and its face will be fully illuminated by the Sun. It will be brighter than any other time of the year and will be visible all night long. This is the best time to view Uranus. Due to its distance, it will only appear as a tiny blue-green dot in all but the most powerful telescopes.


·  October 21, 22 - Orionids Meteor Shower. The Orionids is an average shower producing up to 20 meteors per hour at its peak. It is produced by dust grains left behind by comet Halley, which has been known and observed since ancient times. The shower runs annually from October 2 to November 7. It peaks this year on the night of October 21 and the morning of October 22. The crescent moon will set early in the evening leaving dark skies for what should be a good show. Best viewing will be from a dark location after midnight. Meteors will radiate from the constellation Orion, but can appear anywhere in the sky.


·  November 4 - Full Moon. The Moon will be located on the opposite side of the Earth as the Sun and its face will be will be fully illuminated. This phase occurs at 05:23 UTC. This full moon was known by early Native American tribes as the Full Beaver Moon because this was the time of year to set the beaver traps before the swamps and rivers froze. It has also been known as the Frosty Moon and the Hunter's Moon.


·  November 4, 5 - Taurids Meteor Shower. The Taurids is a long-running minor meteor shower producing only about 5-10 meteors per hour. It is unusual in that it consists of two separate streams. The first is produced by dust grains left behind by Asteroid 2004 TG10. The second stream is produced by debris left behind by Comet 2P Encke. The shower runs annually from September 7 to December 10. It peaks this year on the the night of November 4. Unfortunately the glare from the full moon will block out all but the brightest meteors. If you are extremely patient, you may still be able to catch a few good ones. Best viewing will be just after midnight from a dark location far away from city lights. Meteors will radiate from the constellation Taurus, but can appear anywhere in the sky.


·  November 13 - Conjunction of Venus and Jupiter. A spectacular conjunction of Venus and Jupiter will be visible in the evening sky. The two bright planets will be extremely close, appearing only 0.3 degrees apart. Look for this impressive pairing in the Eastern sky just before sunrise.


·  November 17, 18 - Leonids Meteor Shower. The Leonids is an average shower, producing up to 15 meteors per hour at its peak. This shower is unique in that it has a cyclonic peak about every 33 years where hundreds of meteors per hour can be seen. That last of these occurred in 2001. The Leonids is produced by dust grains left behind by comet Tempel-Tuttle, which was discovered in 1865. The shower runs annually from November 6-30. It peaks this year on the night of the 17th and morning of the 18th. The nearly new moon will not be a problem this year. Skies should be dark enough for what should be good show. Best viewing will be from a dark location after midnight. Meteors will radiate from the constellation Leo, but can appear anywhere in the sky.


·  November 18 - New Moon. The Moon will located on the same side of the Earth as the Sun and will not be visible in the night sky. This phase occurs at 11:42 UTC. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.


·  November 24 - Mercury at Greatest Eastern Elongation. The planet Mercury reaches greatest eastern elongation of 22.0 degrees from the Sun. This is the best time to view Mercury since it will be at its highest point above the horizon in the evening sky. Look for the planet low in the western sky just after sunset.


·  December 3 - Full Moon, Supermoon. The Moon will be located on the opposite side of the Earth as the Sun and its face will be will be fully illuminated. This phase occurs at 15:47 UTC. This full moon was known by early Native American tribes as the Full Cold Moon because this is the time of year when the cold winter air settles in and the nights become long and dark. This moon has also been known as the Full Long Nights Moon and the Moon Before Yule. This is also the only supermoon for 2017. The Moon will be at its closest approach to the Earth and may look slightly larger and brighter than usual.


·  December 13, 14 - Geminids Meteor Shower. The Geminids is the king of the meteor showers. It is considered by many to be the best shower in the heavens, producing up to 120 multicolored meteors per hour at its peak. It is produced by debris left behind by an asteroid known as 3200 Phaethon, which was discovered in 1982. The shower runs annually from December 7-17. It peaks this year on the night of the 13th and morning of the 14th. The waning crescent moon will be no match for the Geminids this year. The skies should still be dark enough for an excellent show. Best viewing will be from a dark location after midnight. Meteors will radiate from the constellation Gemini, but can appear anywhere in the sky.


December 18 - New Moon. The Moon will located on the same side of the Earth as the Sun and will not be visible in the night sky. This phase occurs at 06:30 UTC. This is the best time of the month to observe faint objects such as galaxies and star clusters because there is no moonlight to interfere.


December 21 - December Solstice. The December solstice occurs at 16:28 UTC. The South Pole of the earth will be tilted toward the Sun, which will have reached its southernmost position in the sky and will be directly over the Tropic of Capricorn at 23.44 degrees south latitude. This is the first day of winter (winter solstice) in the Northern Hemisphere and the first day of summer (summer solstice) in the Southern Hemisphere.


December 21, 22 - Ursids Meteor Shower. The Ursids is a minor meteor shower producing about 5-10 meteors per hour. It is produced by dust grains left behind by comet Tuttle, which was first discovered in 1790. The shower runs annually from December 17-25. It peaks this year on the the night of the 21st and morning of the 22nd. The crescent moon will set early in the evening leaving dark skies for optimal observing. Best viewing will be just after midnight from a dark location far away from city lights. Meteors will radiate from the constellation Ursa Minor, but can appear anywhere in the sky.






Saturday, 12 November 2016

২১ শতকের সবচেয়ে বড় আর উজ্জ্বল চাঁদ!




আকাশে চাঁদ দেখতে কে-না পছন্দ করেন! তবে সেই চাঁদ যদি পৃথিবীর সবচেয়ে কাছ থেকে দেখা যায় তাহলে তো কথাই নেই। আর পৃথিবীর সবচেয়ে কাছ থেকে চাঁদ দেখা যায় প্রতি ১৮ বছর পরপর। আগামী ১৪ নভেম্বরে ২১ শতকের সবচেয়ে বড় আর উজ্জ্বল চাঁদটিকে দেখা যাবে আকাশে। তবে এবারই প্রথম আমাদের এই বাসযোগ্য গ্রহ পৃথিবীর খুব কাছে আসছে সুপার মুন, যা এতটা কাছে আসবে না আর কখনোই। ১৯৪৮ সালের পর এত বড় আর এতটা উজ্জ্বল চাঁদ আর দেখা যায়নি আকাশে। পূর্ণিমার চাঁদ যতটা বড় দেখায় তার চেয়ে এবার ১৪ শতাংশ বেশি বড় দেখাবে এই সুপার মুনটিকে। তার উজ্জ্বলতা হবে সাধারণ পূর্ণিমার চাঁদের চেয়ে ৩০ শতাংশ বেশি। কক্ষপথে ঘুরতে ঘুরতে চাঁদের এই পৃথিবীর সবচেয়ে কাছে চলে আসার দূরত্বকে ‘পেরিজি’ বলা হয়। এরপর এমন চাঁদ দেখা যাবে ২০৩৪ সালে।

Supermoon science: November 2016 moon biggest and brightest in 60 years

On Monday, 14 November, the moon will be the biggest and brightest it has been in more than 60 years. So long as the sky is clear of clouds, it should be a great time to get outside and gaze at it or take some photos.  



It’s what is commonly called a “supermoon”, or technically a “perigee full moon” – a phenomenon that occurs when a full moon coincides with the moon being the closest it gets to the Earth on its orbit.
What makes this one special is that the moon is going to be even closer to the Earth than it normally gets, making it a tiny bit bigger than even your average supermoon.
But, despite a lot of hyperbolic news written about the event in the past few days, don’t be too surprised if it looks much like any other full moon.
Wondering what’s really going on and how to catch a glimpse? We’ve got you covered.

How much bigger will it be?

At 8:09PM GMT, the moon will pass by the Earth at a distance of 356,511km – the closest it has passed the Earth since 1948. As it does so, it will be a full moon, making it a particularly big supermoon.
Supermooons are roughly 30% larger in area and 30% brighter than the smallest full moons – full moons that happen when the moon is at its furthest distance from Earth: at “apogee”. In terms of diameter – the width of the moon – it will be about 14% wider than the smallest full moons.
The difference between this unusually big supermoon and other supermoons – like the ones you could have seen on 16 October or you could see on 14 December – is negligible.

How bright will it look?

While a supermoon is 30% brighter than the smallest full moons, it’s only about 15% brighter than an average full moon. That’s nothing to sneeze at – on a clear night, away from city lights, it will provide more moonlight than you’d usually get from a full moon.
But, anywhere near the city, that difference is likely to be difficult to perceive. And, of course, clouds or haze could wipe out the difference, or indeed cover the moon completely.

How big will it look?

When it comes to the size, the difference in width (diameter) between a supermoon and an average moon is about 7%. When the moon is high in the sky, that difference is something you’re unlikely to notice, because the sky is big and there’s nothing to measure it against.
But if you could compare it to a moon at apogee (when it’s farthest) you would probably be able to see the difference. The image below shows that difference.


Supermoon: difference in size between the smallest and largest moon appearances
A supermoon occurs when a full moon coincides with the closest (perigee) position in the moon's orbit, resulting in a moon that appears larger and brighter than normal. Here you can see the size difference compared with the smallest possible full moon (apogee)
 
 

Supermoon and the moon illusion

 

What’s more, the boost in actual size of the moon’s image from a supermoon is totally swamped by what’s known as the “moon illusion”, which affects your perception of the size of the moon.
When the moon is close to the horizon, it can appear up to 300% the size it does when it is high in the sky – which makes much more of a difference than the actual 7% boost you get from it being a bit closer to the Earth.
That moon illusion (as the name suggests) is a complete illusion – the image of the moon does not change significantly at all as it moves from the horizon up into the sky. But, when it is close to the horizon, observers think it looks bigger. Exactly what causes the moon illusion is still a matter of debate. But there are lots of possible explanations.
Nevertheless, if you go out and look at the moon on 14 November, when it is near the horizon, you will get both the psychological effect of the moon illusion, and the physical effect of the supermoon – so it could look particularly striking.

What causes a supermoon?

The moon’s orbit around the Earth is not quite a circle but an ellipse – a kind of squashed circle.
Ellipses are described mathematically with two foci, one at either side of the centre. When an orbit is elliptical, the big body in the middle (the Earth in this case) sits at one of those two foci.
Since the Earth is sitting off to one side of the ellipse, the moon is inevitably closer to the Earth when it passes that side, and further away as it passes the other side.
When it is at the close side (called “perigee”), and it is a full moon, it’s called a supermoon. (That name was actually made up in the pseudoscience field of astrology but it has entered the common lexicon.)
Apogee


Supermoon: orbit showing the closest and most distant points
A supermoon occurs when a full moon coincides with the closest (perigee) position in the moon's orbit, resulting in a moon that appears larger and brighter than normal
 
 

Why are supermoons not all the same size?

 

In short, the reason is that the shape of the ellipse that the moon draws around the Earth is changing all the time as it is pushed and pulled by other gravitational forces.
As a result, how stretched-out the ellipse is changes. When the supermoon coincides with a very stretched out ellipse, a supermoon is even closer (and bigger). That’s what happened in 1948 – and what will happen on Monday.
In more technical terms, the moon’s orbit’s “eccentricity” varies. Mathematically, an ellipse can have an eccentricity between zero and one. If the eccentricity is zero, it is a circle. As the eccentricity closer to one, the ellipse gets more and more stretched-out. Once it reaches one, it breaks open and becomes a parabola.
Now, the moon’s eccentricity has an average value of just 0.0549, making it incredibly close to a circle. But it varies from about 0.0255 to 0.0775, according to Nasa.


Source : https://www.theguardian.com/science/2016/nov/10/the-science-of-supermoons-the-lunar-lowdown-on-the-biggest-and-brightest-in-60-years 
 

Tuesday, 1 November 2016

Celestron Advanced VX 6" f/8 Refractor Telescope






Product Highlights
  • 6" / 150mm Aperture, f/8 Focal Ratio
  • 1200mm Focal Length, 354x Magnification
  • 2" Focus Tube, 20mm Eyepiece
  • 9x50 Finderscope
  • Advanced VX German Equatorial GoTo Mount
  • All-Star Polar Alignment Technology
  • Programmable Periodic Error Correction
  • NexStar Hand Controller
  • Pre-Loaded 40,000 Object Database
  • Adjustable Stainless Steel Tripod  



Overview

The Advanced VX 6" f/8 Refractor Telescope from Celestron is a complete astroimaging platform including a 6" refractor optical tube, 20mm eyepiece, Advanced VX computerized German Equatorial mount, adjustable stainless steel tripod, and NexStar hand controller. By pairing the refractor tube with their redesigned Advanced VX mount, Celestron has created an optical instrument built to satisfy stargazers and astrophotographers.


Celestron's 6" refractor boasts a flatter field of view and brighter deep sky objects than comparably-sized catadioptrics. Unlike Schmidt-Cassegrain and Newtonian optical designs, refractors have an all-glass optical path without a secondary mirror obstructing incoming light. When it comes to lunar, planetary, and wide field imaging, refracting optics transmit faint detail like no other. This configuration of the Advanced VX telescope has a 2" focus tube that enables use of both 2" and 1.25" accessories.
To accommodate the added weight common with refractor optical tubes, the Advanced VX mount includes two eleven-pound counterweights to center the OTA and mount over the tripod. Maintaining the OTA's center of gravity over the tripod prevents excessive strain on the servo motors and helps deliver smooth and precise telescope tracking. The 6" refractor's 1200mm focal length combined with a counterbalanced OTA-mount system translates into crisp long exposure photographs of planetary and deep space objects alike.


Celestron's Advanced VX German-Equatorial mount is an integrated telescope support, alignment and guiding system optimized for astrophotography. Celestron engineered the Advanced VX mount from the ground up to deliver the functionality and affordability required by astroimagers on a budget. This telescope mount delivers some of the features found on more sophisticated German Equatorial mounts but without the added bulk or cost associated with more robust options. The Advanced VX mount is designed to accommodate an optical tube weighting up to 30 lb.


The core technology driving the Advanced VX mount is Celestron's All-Star Polar Alignment. This alignment system features a 2-Star alignment mode that uses multiple guide stars to assist tracking across the night sky while keeping the optical tube parallel to the Earth's axis of rotation. Maintaining alignment with either celestial pole while following the path of guide stars provides a high degree of pointing and tracking accuracy. Digitally-encoded low-cog DC servo motors drive telescope movements on both axes in fine increments that keep the observed (or photographed) object centered in the field of view. This level of precision reduces optical aberrations and minimizes star trails, which translates into improved image quality and sharper photographs.


Complementing the Advanced VX's alignment and tracking capability is the mount's permanently programmable periodic error correction that eliminates recurring track errors inherent to all worm drives. Additionally, a 7-77° latitude range enables extended observations and photo exposures by allowing the telescope to track passed the meridian without the meridian flip common with German Equatorial mounts.
Included with the Advanced VX mount is the NexStar hand controller that will slew the telescope to any planetary, stellar, or nebulous object in its pre-loaded database at the touch of a button. The NexStar controller software is flash upgradeable, which allows operating system updates and even refinements to telescope-specific functions. This computerized mount is also compatible with Celestron's proprietary NexRemote telescope control software, which enables the observer to control the telescope using their personal computer.



This fully-integrated telescope mounting system also includes an adjustable stainless steel tripod that has two-inch diameter legs, locking spreader, and a caddy for the NexStar hand controller. The combination of digitally encoded servo motors, broad tracking latitude, and an array of sophisticated alignment and tracking technology equip the Advanced VX with the mechanical precision needed to observe and photograph any nearby or deep sky object.


In addition to the 6" optical tube, NexStar hand controller, Advanced VX German-Equatorial mount and tripod, this telescope includes a 9x50 finderscope for easy object acquisition and a 20mm eyepiece equaling 60x magnification when mounted. This collection of components makes the Advanced VX 6" Refractor a full-featured telescope for a wide range of stargazing and astroimaging applications.
Optical Tube Assembly 
 
  • Refractor optical design, aluminum construction
  • 2" focuser also accommodates 1.25" accessories
  • 6" (150mm) aperture, f/8 light gathering
  • 1200mm focal length, 354x maximum magnification
  • 20mm eyepiece with 60x magnification
  • 19 lb (8.6kg) OTA weight   

Advanced VX German Equatorial Mount 
 
  • Computerized go-to capability
  • 30 lb (13.6kg) payload capacity
  • 7-77° latitude range for tracking passed meridian
  • Permanently programmable periodic error correction
  • All-Star Polar Alignment with 2-Star alignment mode
  • Eq North / Eq South tracking modes, Sidereal / Solar / Lunar tracking rates
  • Digitally-encoded low-cog DC servo motors on both axes
  • Dedicated Autoguider communication port
  • Two AUX communication ports
  • 17 lb (7.7kg) mount weight
  • Includes 12" counterweight bar with two 11 lb weights
NexStar+ Hand Controller
 
  • Pre-loaded 40,000 object database
  • Flash upgradeable operating system
  • LED-backlit interface buttons
  • RS-232 serial communication port
  • Selectable language programming (English, French, German, Italian, Spanish)
Tripod
  • Stainless steel construction
  • 2" diameter upper leg
  • 44-64" (112.8-162.6 cm) height adjustment
  • 18 lb (8.2kg) tripod weight




 Optical Design

Refractor
Aperture 6" (150 mm)
Focal Length 1200 mm
Focal Ratio f/8
Highest Useful Magnification 354.0x
Resolution 0.93 arc sec (Rayleigh), 0.77 arc sec (Dawes)
Finderscope 9 x 50
Eyepiece 20mm (60x)
Optical Tube Length 51" (1.3 m)
Optical Tube Weight 19 lb (8.6 kg)
Tripod Yes
Mount Type German Equatorial
Power Supply 12V DC 3.5A (tip positive)
GO-TO Capability Yes
Altitude / Latitude Adjustment 7 - 77°
Motor DC servo motor, digitally encoded low-cog drive
Load Capacity 30 lb (13.6 kg)
Counterweight (2) 11 lb (5 kg)
Tracking Method EQ North, EQ South
Tracking Rates Sidereal, solar, and lunar
Slew Speed 9 speeds, 4° per sec (maximum)
Alignment Solar System align, Quick align, Last align, 2-star align, 1-star align
Hand Controller NexStar
Communication Port (2) AUX ports, Autoguider
Onboard Celestial Object Database 40,000 objects (upgradeable)
Total Weight 71 lb (32 kg)


Packaging Info
Package Weight 102.0 lb
Box Dimensions (LxWxH) 0.1 x 0.1 x 0.1"


 
In the Box 
Celestron Advanced VX 6" f/8 Refractor Telescope

  • Advanced VX Computerized German Equatorial Mount
  • 20mm Eyepiece
  • Tripod
  • NexStar+ Hand Control (EQ)
  • Two Year Limited Warranty 


  • More information: 

    https://www.bhphotovideo.com/c/product/917578-REG/celestron_22020_advancd_vx_6_refractor.html

     http://www.celestron.com/browse-shop/astronomy/telescopes/advanced-vx-6-refractor-telescope



    Total Price for Bangladeshi users :  

    220,000 BDT. ( Include : Shipping cost, TAX,VAT,AIT and Speedy money. )






    Sunday, 13 March 2016

    পূর্ণ সূর্যগ্রহণের সৌন্দর্য দেখল ইন্দোনেশিয়াবাসী


    ইন্দোনেশিয়ার বিস্তীর্ণ এলাকায় বুধবার পূর্ণ সূর্যগ্রহণ হয়েছে সময় মুসলিম সম্প্রদায়ের অনেকে ইবাদত-বন্দেগি করেন বিভিন্ন জাতি-গোষ্ঠী তাদের আচার-অনুষ্ঠান পালন করে

    বার্তা সংস্থা এএফপির খবরে বলা হয়েছে, ৯ মার্চ ২০১৬ তারিখ স্থানীয় সময় ভোর ছয়টা ১৯ মিনিট (গ্রিনিচ সময় ২৩ টা ১৯ মিনিট) থেকে পৃথিবী সূর্যের মধ্যে যেতে শুরু করে চাঁদ এর প্রায় ঘণ্টাখানেক পর চাঁদ সূর্যকে পুরোপুরি ঢেকে ফেলে, তখন দেশটির পশ্চিম অংশে পূর্ণ সূর্যগ্রহণের দেখা মেলে মুহূর্তেই চারপাশে নেমে এল রাতের অন্ধকার  

    বাংলাদেশ, নেপাল, থাইল্যান্ড, চীন, জাপান, দক্ষিণ কোরিয়াসহ এশিয়ার বিভিন্ন দেশ অস্ট্রেলিয়ার কিছু অংশের বাসিন্দারাও আজ আংশিক সূর্যগ্রহণ দেখেছেন  

    ধরণীর বুকে পূর্ণ আংশিক সূর্যগ্রহণের এমন সৌন্দর্য দেখার জন্য বিভিন্ন দেশের উৎসাহী মানুষ রাস্তায় নেমে আসে কেউ কেউ চলে যায় ছাদসহ উঁচু স্থানে চোখে বিশেষ ধরনের চশমা পরে তারা সূর্যগ্রহণ দেখে পূর্ণ সূর্যগ্রহণকে কেন্দ্র করে  


    ইন্দোনেশিয়ার বিভিন্ন দ্বীপে পর্যটকদের ঢল নামে উপলক্ষে তাই ছিল বিশেষ আয়োজন ছিল মজার দৌড় ড্রাগন নৌকার প্রতিযোগিতাসহ নানা উৎসব এই সৌন্দর্য উপভোগ করার জন্য সুদূর যুক্তরাষ্ট্র থেকে ইন্দোনেশিয়ার বেলিতুং দ্বীপে আসেন ৫২ বছর বয়সী পর্যটক ডেনিয়েল অরেঞ্জ তিনি বললেন, ‘এটা অসাধারণ সব মিলিয়ে সূর্যগ্রহণ দেখার ব্যাপারটা ছিল সুন্দর এখানে অনেকে জড়ো হয়েছিলেন যখন পূর্ণ সূর্যগ্রহণ হলো, তখন সবাই উল্লাস করে উঠল