The Moon is the Moon, if you go around calling it Luna people will think you are a lunatic :)Quote:
Originally Posted by Dreamwoven
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The Moon is the Moon, if you go around calling it Luna people will think you are a lunatic :)Quote:
Originally Posted by Dreamwoven
This is an update from the journal blog..
That was an amazing blog post by Marc Rayman. It looks like ion propulsion works getting Dawn to visit both Vesta and Ceres.
Now to find out what those two bright spots are.
I just finished reading Bob Berman's article in the April "Astronomy" in the library called "Dark vs super dark". He was commenting on how bright the sky is for most of us. He wrote this about super dark places:
The Milky Way "pops" and totally dominates the sky dome. It casts shadows.
I can barely see the Milky Way, let alone any shadows.
The nights have been clear and I have been able to see Venus and Jupiter clearly. it is also warmer. According to Sky Map Uranus and Mars were in near conjunction. What amazed me was how high the ecliptic was. Of course, I knew the sun got higher in the sky, but I didn't really think about it before. I am going to try to find Saturn.
Have you managed to see the Zodiacal light? It occurs just after full dark and In the spring it can be seen in the southwest. In the autumn it is a pre-dawn phenomena.
I can't see the spring Zodiacal light. Too many trees in that direction and made impossible by the tall road junction double street corner lights. I will look again in the autumn when it will be pre-dawn and so in the northeast, which should be easier.
The Exozodiacal dust is the name for the phenomena on other planets.
It is meant to be the sunlight reflected off cosmic dust. In Islam the false dawn of this zodiacal light has an important place in the timing of the five daily prayers. You can read about it here: http://en.wikipedia.org/wiki/Zodiaca...tance_to_Islam.
I haven't seen the zodiacal light. With the light pollution where I am I would probably not be able to, however, I will keep that in mind as something to look for when I get to Wisconsin later this Spring. Sometimes the skies there are very dark and the "seeing" is clear. I was planning to look for Saturn but I would have to get up early. There is a park I could walk to where it is darker, but I plan to drive to Lake Michigan one of these days and watch the Sun rise.
Trying to find the direction to Mecca (qibla) is an interesting problem. Although I understand the astrolabe would help with this, I don't see how this works. Come to think of it, there is probably an app for the phone that would show this direction.
This from earth sky (15 March) suggests that Jupiter's largest moon, Ganymede, may have oceans beneath its ice: http://earthsky.org/space/underground-ocean-on-jupiters-largest-moon
Nice article. I didn't know Ganymede had aurorae. That would mean Ganymede has a magnetic field. Although I don't follow how the interference between Jupiter's magnetic field and Ganymede's implies there is an ocean below, it seems plausible. I was amazed at how deep the ocean and ice are predicted to be.
This morning I saw the old moon as the sun rose. I guess we will have a new moon for the vernal equinox.
Have to agree with that. EarthSky has a post on Ceres, I wondered why it was taking so long for Dawn to get better images, it has been in orbit round Ceres for a couple of days or more. It seems it will be gradually going lower in orbit, presumably using its ion propulsion to brake, until it can start to map and investigate the dwarf planet, in a couple of weeks time. Here is a quote:
Fortunately, we won’t have to wait much longer before we get some more definitive answers to questions of Ceres’ physical structure and heritage. By the beginning of April, the Dawn spacecraft will be much closer and will start its imaging campaign in earnest, at which point we will start seeing craters and other surface features at better resolution
Those two bright spots on Ceres are what interest me the most.
It might be a long wait…
I've been having a look at Vesta, the largest asteroid in the solar system.
As I'm writing this I'm watching the solar eclipse in the uk - not total, only 80% where I am. It's 9.45 am GMT here and 80% happened around 9.30, I could see a crescent sun that indeed looked about 20%! The sky was still quite bright - brighter than before the clouds cleared. (I'm amazingly lucky to have seen this, it was forecast to be total cloud cover, but it cleared at just the right time.)
When I realised it was sunny I hurriedly made a simple pinhole camera. "Don't stare directly at the sun, folks," as they keep on saying. To do that use a pin to make a small hole in a piece of photocopy paper, with a pin, than project the image of the sun onto another piece of photocopy paper. The image you get is small (dime size) but you can easily see the moon covering the sun, and the change in the amount of cover, which happens over several minutes.
The birds are making some strange chirping noises. It's definitely getting brighter as the minutes wear on. A dog is barking. The neighbours are giving me strange looks as I manipulate two pieces of photocopy paper into strange positions in my garden...
10am now and the moon is now only covering 50/60% of the sun.
The BBC hired a plane to fly above the clouds and capture totality:
http://www.theguardian.com/science/l...e-live-updates
Still my less expensive approach was 80% as good, I reckon, for a lot less than 20% of the effort! It's great to actually go out into your garden and do this rather than watching it on the web. I can say I was there :)
I saw the partial eclipse too. It got noticeably darker when it happened between 10.50 and 11.05, and the birds went quiet. Animals know its happening, which I find fascinating. I reckon it got 50 percent partial eclipse in Sweden: http://www.thelocal.se/20150320/swed...-solar-eclipse
It is interesting that animals may have sensed it. It does get darker.
The last time I saw a total eclipse was almost two decades ago. Many of us were out looking through pinholes in paper but underneath a maple tree we could see projected on the sidewalk many tiny eclipses showing through the leaves of the tree.
I have jet read about the new James Webb Telescope to be launched in 2018. You can read about it here.
In looking at Wikipedia (http://en.wikipedia.org/wiki/James_Webb_Space_Telescope) this telescope would collect five times as much light and be focused on the infrared. I can see how one can collect more radiation: just build a bigger surface. But I don't know what it means to focus on the infrared. The position of the telescope would be at a Lagrangian point in earth's orbit around the Sun. I suppose it would not be able to be repaired as easily as Hubble in low-earth orbit.
Good points!
I had also not thought of the problem of making repairs so far out in space.
I am hoping to see the lunar eclipse tomorrow morning. It would be about 5:16 my time in Chicago. There is a good chance I will be asleep, but I wasn't able to see the solar eclipse a couple weeks ago since it was at night my time.
It turns out I woke up early enough this morning to see the Moon get almost completely eclipsed before it disappeared in the clouds above my neighbor's house in the west.
I was hoping to see the moonshadows disappear, but dawn made them disappear first.
Also, considering the curvature of the Earth's shadow on the Moon, clearly the Earth is far bigger than the moon. I wonder if there are such things as the Earth's shadow eclipsing outer planets such as Mars and Jupiter. I'll have to look that up. The Earth would not eclipse Venus or Mercury since they are closer to the Sun than the Earth and so the Earth can't get in the way of the Sun's light.
A lunar eclipse shows the moon as red, as this is the colour that is visible through the earth's atmosphere. See https://en.wikipedia.org/wiki/Lunar_eclipse. I don't think the shadow of the earth projects far enough to eclipse any of the outer planets, but such events certainly happen when the earth comes between the sun and any of its planets.
I found a very nice astronomy blog from Northern Ireland, http://www.armaghplanet.com/blog/ divided up into solar system, our galaxy, universe, and a miscellany category weird and fun. Its well written and very informative. The Armagh Planetarium has its own webpage, too: http://www.armaghplanet.com.
The article about the solar flyby 70,000 years ago and the four species of humans alive then was pretty interesting: http://www.armaghplanet.com/blog/did...ent-skies.html
As far as those four species, I knew about the Neanderthal, but not the Denosovan nor Homo floresciensis.
Yet another probe that I had never heard of - this time Japanese, Akatsuki - that missed its orbit around Venus and went round the sun instead. It has also got boost propellent (not sure what kind) but its back and on track for its orbiting around Venus. See also this Astronomy Now piece.
I had not heard of Akatsuki before either. From the links, it will be looking for lightning and volcanic activity if it gets into orbit around Venus. I wonder why lightning would be of interest. I can see how volcanic activity would show that the planet is still active.
There seem to be a number of large objects circling the sun between Jupiter and Pluto. This one from space.com is about a Centaur, Chiron:
After its discovery in 1977, Chiron was classified as the first "centaur" — a body between Jupiter and Pluto with characteristics common to both asteroids and comets. Today, there are more than 200 known centaurs, and scientists estimate that there are more than 44,000 of these hybrid asteroid-comets in the solar system.
Thats amazing, Chiron has rings around it, like Saturn. It is large, too, minor planet, comet-asteroid, it is 145 miles wide.
Read more about it here: http://www.space.com/29067-chiron-ce...kly_2015-04-13.
I didn't think rings were common either. It looks like the difference between asteroids and comets is one has more metal and the other has more ice to form tails. I guess the combination has some of both.
First fuzzy shots of Pluto, from earthsky:
Here's a link showing the bright spots on Ceres which may be made of ice: http://www.nature.com/news/mystery-o...-grows-1.17313
Popular Astronomy sends subscribers email updates from time to time. Some of these are quite interesting. Below is a part of one which is on Mars. Funnily enough Immanuel Velikovsky wrote about this in the 1950s, that Venus was originally a comet (or perhaps a giant asteroid captured by the earth's gravitational pull to bring it into orbit and the clashes with Mars over many generations (I think it was every 50 years) took place until Venus established itself in a separate orbit.
Anyway, I was fascinated by the book on this I read, Earth in Upheaval, as well as the first of two books on how the ancient history of Egypt got muddled up with repeating events 50 years apart (Ages in Chaos).
METEORITE MAY REPRESENT BULK OF MARS' CRUST
Brown University
NWA 7034, a meteorite found a few years ago in the Moroccan desert, is like no other rock ever found on Earth. It has been shown to be a 4.4-billion-year-old piece of the crust of Mars and, according to a new analysis, rocks just like it may cover vast swaths of Mars. In a new paper, scientists report that spectroscopic measurements of the meteorite are a spot-on match with measurements from orbit of the Martian dark plains, areas where the planet's coating of red dust is thin and the rocks beneath are exposed. The findings suggest that the meteorite is representative of the 'bulk background' of rocks on the Martian surface. When scientists started analyzing the meteorite in 2011, they knew that they had something special. Its chemical make-up confirmed that it came from Mars, but it was unlike any other Martian meteorite. Previously, all the Martian rocks found on Earth were classified as SNC meteorites (shergottites, nakhlites, or chassignites). They are mainly igneous rocks made of cooled volcanic material, but the new object is a breccia, a mash-up of different rock types welded together in a basaltic matrix. It contains sedimentary components that match the chemical make-up of rocks analyzed by the Mars rovers. Scientists concluded that it is a piece of Martian crust -- the first such sample to be found on the Earth.
Scientists thought it might help to clear up a long-standing enigma: spectra obtained from SNC meteorites never quite match remotely-sensed spectra from the Martian surface. So after acquiring a chip of the meteorite, they used a variety of spectroscopic techniques to analyze it. The researchers say that the spectral match suggests that the 'dark plains' on Mars are dominated by brecciated rocks similar to the new meteorite. Because the dark plains are dust-poor regions, they are thought to be representative of what lies beneath the red dust on much of the rest of the planet. The researchers claim that, in the light of what is known about Mars, the idea that the surface would be rich in such breccias makes sense. Mars has more than 400,000 impact craters more than 1 km in diameter. Because brecciation is a natural consequence of impacts, it is to be expected that material similar to NWA 7034 has accumulated on Mars over time. In other words, many of the rocks on the surface of Mars are probably very similar to the meteorite.
The first 3 volumes of Velikovsky were Worlds in Collision (about Mars and Venus as Venus jostled with Mars to clear her orbit, Earth in Upheaval looking at the evidence for violent upheavals on earth, and Ages in Chaos, which look at periods of history which historians unwittingly duplicated. The first was From the Exodus to King Akhnaton which deals with the Israeli exodus and crossing the Red Sea when the waters part. The book is very scholarly and I am not able to judge it as I can't read the Old Testament Book of Exodus in its original Hebrew, but it seems to me that he makes a case for the fact that scholars made an erroneous duplication of ancient history, based on the series of plagues and the violent physical upheavals in the Middle East. I have not read Vol. 2 of Ages in Chaos: Ramses II and His Time but the 2 volumes put the case for a double-counting of the plagues and upheavals that were the results of the periodic Mars-Venus near-collisions. Another Volume Mankind in Amnesia explains the disjunction as a collective amnesia on the part of historians of the time.
Velikovsky's massive work was subject to a storm of critique and led to the banning of his books by so many prominent historians of the time that the publishers caved in and withdrew the books from publication. This was the 1950s when the Cold War was at its height. But I also read Alfred De Grazia The Velikovsky Affair (published in 1966) which attempted to defend Velikovsky. The worst period of McCarthyism was over but the damage had been done by then.
His works have been re-published in their original entirety in 2009 (paperbacks) by Paradigma Books.
I had not thought of Venus being originally a comet or asteroid before. It is even amazing to me that brecciated rocks from Mars' surface can reach the Earth. Although Velikovsky's view seems unusual, one way to check it is to see how long ago Venus was recognized in the sky as a planet.
Yes, that is one way. Velikovsky goes into this in some detail. The 4 planet system - Saturn, Jupiter, Mars, Mercury - were identified in the ancient hindu table of planets, Venus was not there (planet in Greek means "wanderer", as the planets did not follow the stable pattern of the sun and moon). Later they realised that this was because they don't go round earth as they at first believed but round the sun. Venus was a comet as it had a "tail", it "smoked".
That is it in a nutshell.
It looks like Velikovsky's theory passed my initial attempt at falsification. It makes me wonder what those early Hindus thought about Venus.
i wonder why beltQuote:
Originally Posted by free
this is usually something you buckle
or the expression
a belter
but three to form a belt is rather strange
The belt is just one obvious part of the constellation of Orion (the hunter) which looks a bit like an archer shooting a bow. The belt is very distinctive, and the easiest to distinguish. I can't find an image of the entire constellation, but this one of the belt and the armpit of Orion (Betelgeuse) is the best I can find atm.
OK I found it, middle picture here.
thanks i find the names given rather hidden.Quote:
Originally Posted by Dreamwoven
I am not quite sure why hunter exactly but there you go each to their dreams.:)Quote:
Originally Posted by Dreamwoven
I agree, it is a bit Rorschach-like and why the lines are drawn between stars they way they are is never explained. Bt seeing the whole of the Orion constellation I can see the left arm raised and two stars being the fingers of the left arm, after loosing an arrow. Orion also has 2 hunting dogs - Canis Major and Canis minor. I can't for the life of me see a dog in either of these constellations. Canis Major includes the brightest star in the heavens, Sirius.
But how they work out the names of the constellations is beyond me.
The text below is from the Society for Popular Astronomy. It shows the extreme violence of interstellar space.
At our London meeting this Saturday, 25 April, our Vice President, Prof. Tim O'Brien, will talk about novae – exploding stars.
Several times each year a new star appears in the night sky. Dubbed novae by astronomers of the past, we now know these are explosions on white dwarfs in binary star systems which can eject around an Earth’s mass of material into space at speeds of thousands of kilometres per second. The white dwarf is not destroyed in these outbursts and the nova lives to explode again – in some cases within the lifetime of a single astronomer.
Novae are now detected right the way across the spectrum from radio waves to gamma rays. Prof. O'Brien will describe the latest observations and what they teach us about these interesting astrophysical phenomena – stellar explosions that are sometimes visible to the unaided eye from our own backyards!
This replaces the talk by Dr Lewis Dartnell previously advertised.
Following the break, Robin Scagell talks about forthcoming events in the night sky, and Dr David Mannion looks at The Future of Space Travel. Where will we go after the tremendous Apollo missions, the Mars Rover and the exploration of our Solar System by interplanetary robots? Will we have bases on the Moon and Mars by the end of the 21st Century?
The meeting takes place at SOAS, University of London, starting at 2 pm. More details, and a map of how to get there, are given on the SPA website.