APOD and General Astronomy Discussion Forum
https://asterisk.apod.com/
The Celestron FirstScope was also my first scope. It's a fine little instrument. But be careful. Telescopes are addictive.MargaritaMc wrote:I will be receiving my first telescope in the next week or so and it is ALSO a Celestron - Celestron 76mm Firstscope... Not quite in the same league as the ISS!
http://newswatch.nationalgeographic.com/2013/01/24/dung-beetles-navigate-via-the-milky-way-an-animal-kingdom-first/ wrote:
Dung Beetles Navigate Via the Milky Way, First Known in Animal Kingdom
Posted by Christine Dell'Amore of National Geographic News in Weird & Wild on January 24, 2013
<<Talk about star power—a new study shows that dung beetles navigate via the Milky Way, the first known species to do so in the animal kingdom. The tiny insects can orient themselves to the bright stripe of light generated by our galaxy, and move in a line relative to it, according to recent experiments in South Africa. “This is a complicated navigational feat—it’s quite impressive for an animal that size,” said study co-author Eric Warrant, a biologist at the University of Lund in Sweden.
Moving in a straight line is crucial to dung beetles, which live in a rough-and-tumble world where competition for excrement is fierce. Once the beetles sniff out a steaming pile, males painstakingly craft the dung into balls and roll them as far away from the chaotic mound as possible, often toting a female that they have also picked up. The pair bury the dung, which later becomes food for their babies.
But it’s not always that easy. Lurking about the dung pile are lots of dung beetles just waiting to snatch a freshly made ball. That’s why ball-bearing beetles have to make a fast beeline away from the pile. “If they roll back into the dung pile, it’s curtains,” Warrant said. If thieves near the pile steal their ball, the beetle has to start all over again, which is a big investment of energy.
Seeing Stars
Scientists already knew that dung beetles can move in straight lines away from dung piles by detecting a symmetrical pattern of polarized light that appears around the sun. We can’t see this pattern, but insects can thanks to special photoreceptors in their eyes. But less well-known was how beetles use visual cues at night, such as the moon and its much weaker polarized light pattern. So Warrant and colleagues went to a game farm in South Africa to observe the nocturnal African dung beetle Scarabaeus satyrus.
Attracting the beetles proved straightforward: The scientists collected buckets of dung, put them out, and waited for the beetles to fly in. But their initial observations were puzzling. S. satyrus could still roll a ball in a straight line even on moonless nights, “which caused us a great deal of grief—we didn’t know how to explain this at all,” Warrant said. Then, “it occurred to us that maybe they were using the stars—and it turned out they were.”
To test the star theory, the team set up a small, enclosed table on the game reserve, placed beetles in them, and observed how the insects reacted to different sky conditions. The team confirmed that even on clear, moonless nights, the beetles could still navigate their balls in a straight line.
To show that the beetles were focusing on the Milky Way, the team moved the table into the Johannesburg Planetarium, and found that the beetles could orient equally well under a full starlit sky as when only the Milky Way was present.
Lastly, to confirm the Milky Way results, the team put little cardboard hats on the study beetles’ heads, blocking their view of the sky. Those beetles just rolled around and around aimlessly, according to the study, published recently in the journal Current Biology.
Dung beetle researcher Sean D. Whipple, of the Entomology Department at the University of Nebraska-Lincoln, said by email that the “awesome results …. provide strong evidence for orientation by starlight in dung beetles.” He added that this discovery reveals another potential negative impact of light pollution, a global phenomenon that blocks out stars. “If artificial light—from cities, houses, roadways, etc.—drowns out the visibility of the night sky, it could have the potential to impact effective orientation and navigation of dung beetles in the same way as an overcast sky,” Whipple said.
Study co-author Warrant added that other dung beetles likely navigate via the Milky Way, although the galaxy is most prominent in the night sky in the Southern Hemisphere. What’s more, it’s “probably a widespread skill that insects have—migrating moths might also be able to do it.” As for the beetles themselves, they were “very easy to work with,” he added. “You can do anything you want to them, and they just keep on rolling.”>>
Thank you for the info, Luigi. I have a small map of the Buenos Aires area of Argentina and have been trying to work out where you took the photograph - I had been assuming that you were facing West, which confused me. I am still trying to guess where you were standing. I have a neighbour who is from Buenos Aires and several Argentinian friends and would like to show them this photograph and be able to tell them exactly where it was taken.luigi wrote:Thank you again for the nice comments I'm really happy that you liked the image and I'm also happy to share the south hemisphere skies with my fellow North Hemisphere sky-watchers.
I used calsky to predict the ISS pass, it's very easy to see with the naked eye, you will see it dimming in brightness when the shot was taken. It moved from right to left.
The ISS was at magnitude -2, it can be much brighter with the Sun 21 degrees below the horizon.
This is the information for this ISS pass:
Appears 22h41m27s 0.1mag az:290.4° WNW horizon
Culmination 22h46m47s -2.0mag az:212.4° SSW h:35.8°
distance: 695.9km height above Earth: 430.2km elevation of Sun: -21° angular velocity: 0.62°/s
at Meridian 22h47m36s -1.8mag az:180.0° S h:30.8°
Disappears 22h52m13s 0.2mag az:134.4° SE horizon
Margarita,MargaritaMc wrote:
Thank you for the info, Luigi. I have a small map of the Buenos Aires area of Argentina and have been trying to work out where you took the photograph - I had been assuming that you were facing West, which confused me. I am still trying to guess where you were standing. I have a neighbour who is from Buenos Aires and several Argentinian friends and would like to show them this photograph and be able to tell them exactly where it was taken.
¡ Muchísimas gracias!
Margarita
Tandil is beautiful, the rocks in Tandil are part of the Tandilia system and are among the oldest rock formations on earth, about 2000 millon years old (I wrote that number right). Back then they were as high as the Himalayas and Earth was only populated by simple organisms. Thousands of years of erosion reduced that magnanimous system to hills about 400-500 meters high.MargaritaMc wrote:Got it! Thank you, Luigi.
My friends Marta and Alejandra come from Tandil - I hadn't realised it was still the province of BA . Argentina really is vast.
Margarita
luigi wrote:
Tandil is beautiful, the rocks in Tandil are part of the Tandilia system and are among the oldest rock formations on earth, about 2000 millon years old (I wrote that number right). Back then they were as high as the Himalayas and Earth was only populated by simple organisms. Thousands of years of erosion reduced that magnanimous system to hills about 400-500 meters high.
http://wordlesstech.com/2011/03/31/tandilia-system-oldest-rock-formations-on-earth/ wrote: Tandilia System- oldest rock formations on Earth
by wordlesstech team
<<The system stretches approximately 350 km across the Argentine province of Buenos Aires from Olavarria southeast to Cape Corrientes where it enters the Atlantic Ocean between the cities of Mar del Plata and Miramar. The system is built on two billion year old igneous and metamorphic rock that most likely was a part of the supercontinent Rodinia when its coasts were uplifted during the Paleoproterozoic Era. Over a period of hundreds of millions of years, layers of stratified sediments built up on this base. Many of these sediments, particularly those from the Lower Ordovician, consist of quartz arenite and claystones containing an abundance of fossils and offer insights into life on Earth after the Cambrian–Ordovician extinction event of 488 million years ago. Small hills about 500 m high are all that remain of this once mighty mountain range.>>
http://en.wikipedia.org/wiki/Gondwana wrote: <<In paleogeography, Gondwana originally Gondwanaland, was the southernmost of two supercontinents (the other being Laurasia) that were part of the Pangaea supercontinent. It existed from approximately 510 to 180 million years ago (Mya). Gondwana is believed to have sutured between ca. 570 and 510 Mya, thus joining East Gondwana to West Gondwana. It separated from Laurasia 200-180 Mya (the mid Mesozoic era) during the breakup of Pangaea, drifting further south after the split. Gondwana included most of the landmasses in today's Southern Hemisphere, including Antarctica, South America, Africa, Madagascar and the Australian continent, as well as the Arabian Peninsula and the Indian subcontinent, which have now moved entirely into the Northern Hemisphere.
The continent of Gondwana was named by Austrian scientist, Eduard Suess, after the Gondwana region of central northern India (from Sanskrit gondavana "forest of the Gonds"), from which the Gondwana sedimentary sequences (Permian-Triassic) are also described. The adjective Gondwanan is in common use in biogeography when referring to patterns of distribution of living organisms, typically when the organisms are restricted to two or more of the now-discontinuous regions that were once part of Gondwana, including the Antarctic flora. For example, the Proteaceae, a family of plants known only from southern South America, South Africa and Australia, are considered to have a "Gondwanan distribution". This pattern is often considered to indicate an archaic, or relict, lineage.
The assembly of Gondwana was a protracted process. Several orogenies led to its final amalgamation 550–500 Mya at the end of the Ediacaran, and into the Cambrian. The final stages of Gondwanan assembly overlapped with the opening of the Iapetus Ocean between Laurentia and western Gondwana. During this interval the Cambrian explosion occurred. Gondwana was formed from the following earlier continents and microcontinents, among others, colliding in the following orogenies:
- Azania: much of central Madagascar, the Horn of Africa and parts of Yemen and Arabia.
The Congo–Tanzania–Bangweulu Block of central Africa.
Neoproterozoic India: India, the Antongil Block in far eastern Madagascar, the Seychelles, and the Napier and Rayner Complexes in East Antarctica.
The Australia/Mawson continent: Australia west of Adelaide and a large extension into East Antarctica.
Other blocks which helped to form Argentina and some surrounding regions, including a piece transferred from Laurentia when the west edge of Gondwana scraped against southeast Laurentia in the Ordovician. This is the Famatinian block (named after Famatina in northwest Argentina) and it formerly continued the line of the Appalachians southwards.>>
Marta (who is in her late 70s and misses Argentina very much) has told me how very beautiful Tandil is, so I have some idea. But I had no idea that the rocks of the area were SO old. Is this the area that Charles Darwin spent so long in when he was taking time out from the Beagle? (The Voyage of the Beagle is one of my favourite books) He was very impressed with Argentina, both the geology, the landscape, and the people. He spent long journeys with gauchos and admired them very much indeed.luigi wrote:
Tandil is beautiful, the rocks in Tandil are part of the Tandilia system and are among the oldest rock formations on earth, about 2000 millon years old (I wrote that number right). Back then they were as high as the Himalayas and Earth was only populated by simple organisms. Thousands of years of erosion reduced that magnanimous system to hills about 400-500 meters high.
It's amazing!
I was having a "senior moment" ... I meant, of course, facing East! The confusion came in trying to work out where the ocean would be if you were in the city of Buenos Aires. (But, if truth be told, I do have to think carefully to work out east and west...I had been assuming that you were facing West, which confused me.
)Not quite the oldest on Earth, though very old, obviously. I've stood on a narrow streak of rock which was 3.5 billion years old, according to a geologist who was investigating it, in northern New Brunswick. More of it appears in Labrador and elsewhere in the vast Canadian Shield. Apparently the oldest rock formation found so far is greater than 4 billion years old. The 2 billion year old Tandilia System is only middle-aged by comparison.neufer wrote:[url]http://wordlesstech.com/2011/03/31/tandilia-system-oldest-rock-formations-on-earth/[/url] wrote:
Seen above are the remains an ancient mountain range and one of the oldest rock formations on Earth known as the Tandilia System, named for the nearby town of Tanadil.
If it's so old why is it called NEW Brunswickrstevenson wrote:
Not quite the oldest on Earth, though very old, obviously. I've stood on a narrow streak of rock which was 3.5 billion years old, according to a geologist who was investigating it, in northern New Brunswick. More of it appears in Labrador and elsewhere in the vast Canadian Shield. Apparently the oldest rock formation found so far is greater than 4 billion years old. The 2 billion year old Tandilia System is only middle-aged by comparison.
Be careful of that one, Art.neufer wrote:rstevenson wrote:
Not quite the oldest on Earth, though very old, obviously. I've stood on a narrow streak of rock which was 3.5 billion years old, according to a geologist who was investigating it, in northern New Brunswick. More of it appears in Labrador and elsewhere in the vast Canadian Shield. Apparently the oldest rock formation found so far is greater than 4 billion years old. The 2 billion year old Tandilia System is only middle-aged by comparison.
By a happy coincidence Sky and Telescope's This Week's Sky at a Glance gives more detailed instructions for finding Canopus.Anthony Barreiro wrote:MargaritaMc wrote:
I wonder if I would be able to see Canopus from here in Tenerife? I had not realised how near to Sirius it is. We are 28°N 16°W.Canopus is almost exactly south of Sirius, so (from the northern hemisphere) whenever Sirius is at its highest due south, Canopus will also be at its highest due south as well.neufer wrote:Yes, provided that you have a clear view to the South, Magarita.
It should be highest around 11:15 PM local time due South (but at only about a quarter of the height of Sirius).
I'm at 37 degrees north latitude, so Canopus theoretically kisses my horizon at culmination, but as a practical matter I would have to travel farther south to hope to see Canopus.Sky and Telescope wrote:•Around 9 or 10 p.m. this week (depending on how far east or west you live in your time zone), brilliant Sirius is at its highest due south.
•Sirius is the brightest star in the night sky — and are you far enough south to see the second brightest, Canopus? In one of the many interesting coincidences that devoted skywatchers know about, Canopus lies almost due south of Sirius: by 36°. That's far enough south that it never appears above your horizon unless you're below latitude 37° N (southern Virginia, southern Missouri, central California). And there, you'll need a flat south horizon. Canopus transits the sky's north-south meridian just 21 minutes before Sirius does.
When to look? Canopus is there at its highest point when Beta Canis Majoris — Mirzim, the star about three finger-widths to the right of Sirius — is at its highest point crossing the meridian. Look straight down from Mirzim then.
I'm pretty sure that that sort of language is not allowed at the Asterisk.Anthony Barreiro wrote:
I'm at 37 degrees north latitude, so Canopus theoretically kisses my horizon at culmination,
Excuse me while I kiss the sky.neufer wrote:I'm pretty sure that that sort of language is not allowed at the Asterisk.Anthony Barreiro wrote:
I'm at 37 degrees north latitude, so Canopus theoretically kisses my horizon at culmination,
How serendipitous. Thanks a lot.Anthony wrote:
By a happy coincidence Sky and Telescope's This Week's Sky at a Glance gives more detailed instructions for finding Canopus.
Yes it is! That's Acrux, the brightest star of the southern Cross.DavidLeodis wrote:I would be grateful if someone could please clarify something. Is the bright star at the top of the Coalsack Nebula part of the Southern Cross (Crux) or not, as information that I have found about the Southern Cross is confusing me? Unfortunately the very useful annotated version of the image in Luis Argerich's website also does not make it clear (at least to me!). It is though a very nice scene.
We only just noticed it.neufer wrote:If it's so old why is it called NEW Brunswick
