Man of Honour
Shockwave from a supernova:
*** The Official Astronomy & Universe Thread ***
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Soldato
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Hey all,
I'm looking to pick up a telescope as a present for the better half's birthday. She's never used a telescope before but is definitely keen on astronomy + space; follows all the ISS and Nasa stuff, watches the launches, enjoys looking at the sky and trying to pick out objects by eye etc. so I'm pretty sure splashing out on something fairly decent isn't going to end up being a mistake. Let's say I'm looking around £200, £300 absolute maximum
I've been reading up on this a fair bit already but since I found this thread I thought why not get some opinions in here too. Having read around I was looking at something like the "Celestron Astromaster 130EQ" plus a 2x Barlow eyepiece to go with it...
I'm looking to pick up a telescope as a present for the better half's birthday. She's never used a telescope before but is definitely keen on astronomy + space; follows all the ISS and Nasa stuff, watches the launches, enjoys looking at the sky and trying to pick out objects by eye etc. so I'm pretty sure splashing out on something fairly decent isn't going to end up being a mistake. Let's say I'm looking around £200, £300 absolute maximum
I've been reading up on this a fair bit already but since I found this thread I thought why not get some opinions in here too. Having read around I was looking at something like the "Celestron Astromaster 130EQ" plus a 2x Barlow eyepiece to go with it...
Soldato
I believe that is the telescope I have!
It is a good starter scope, easy to set up and use - also pretty light so you can pack it up and take it to darker skies without hassle - and can give you some really nice views of star clusters, planets - their moons - and the moon (especially last night
). Poor eye piece quality can ruin the experience and the supplied 10mm eye piece is pretty poor, but the 20mm isn't too bad. The 20mm is an erecting eye-piece, useful when you start out as the non-erecting show you a picture that is upside down. I'd recommend picking something like this up to replace the 10mm and would recommend one of these too. On a clear night, star clusters and the moon with its abundance of craters will fill this eye piece and convert even yourself! 
The quality is immense for the price and what you see is certainly worth the price tag. If she was to upgrade in future, neither of these would be replaced. 
A Barlow (like this) works well with the latter eyepiece (I own these two myself, soon the purchase the 9mm), but I find that with more magnifying eye-pieces, the telescope begins to struggle and the picture becomes too blurred. It is certainly a capable scope and perfect for beginners.
It is a good starter scope, easy to set up and use - also pretty light so you can pack it up and take it to darker skies without hassle - and can give you some really nice views of star clusters, planets - their moons - and the moon (especially last night
). Poor eye piece quality can ruin the experience and the supplied 10mm eye piece is pretty poor, but the 20mm isn't too bad. The 20mm is an erecting eye-piece, useful when you start out as the non-erecting show you a picture that is upside down. I'd recommend picking something like this up to replace the 10mm and would recommend one of these too. On a clear night, star clusters and the moon with its abundance of craters will fill this eye piece and convert even yourself! The quality is immense for the price and what you see is certainly worth the price tag. If she was to upgrade in future, neither of these would be replaced. A Barlow (like this) works well with the latter eyepiece (I own these two myself, soon the purchase the 9mm), but I find that with more magnifying eye-pieces, the telescope begins to struggle and the picture becomes too blurred. It is certainly a capable scope and perfect for beginners.
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An alternative would be the Skyliner 200p or the cheaper 150p, which both have bigger mirrors that would make the image more impressive. I've also heard questionable things about the mounts on those cheaper EQ telescopes, they might be alright but they're not going to be as stable or as easy to use as a dobsonian.
http://www.firstlightoptics.com/beginner-telescopes/skywatcher-skyliner-150p-dobsonian.html
http://www.firstlightoptics.com/beginner-telescopes/skywatcher-skyliner-150p-dobsonian.html
A Barlow (like this) works well with the latter eyepiece (I own these two myself, soon the purchase the 9mm), but I find that with more magnifying eye-pieces, the telescope begins to struggle and the picture becomes too blurred. It is certainly a capable scope and perfect for beginners.
There's a couple of limits to for a scope:
1. dimmer picture - the more magnification, the smaller area of sky and so the less light. This is why as you increase magnification and focal length the image will dim unless you add more aperture to compensate.
2. Dawes limit - basically a scope has a maximum resolution caused by the size of the mirror or lens. Increasing the magnification puts you closer to that limit. Going beyond the limit, the image becomes more and more blurred.
3. Quality of optics - both the scope mirrors/lenses and the eyepieces. Bundled EPs aren't great, and I replaced my first telescope's EPs and it was like having a different telescope!
With a larger aperture and a faster (i.e. lower) f-ratio - you'll be able to see more stars but still have the option to zoom in. For visual between f/4 to f/6.
Soldato
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Thanks for the responses guys, my only concern with the "Skyliner" one is that without a tri-pod doesn't that limit you to standing it on a table or something similar? Or am I not understanding something and actually you can attach it to a tri-pod?
Based on the review above it sounds like the 130EQ might be a good pick... You reckon even without the motorised tracking computer thing a beginner can pick up how to find some different objects in the sky without too much difficulty? (certainly the Moon I guess is pretty easy, but some of the other planets and things?)
Based on the review above it sounds like the 130EQ might be a good pick... You reckon even without the motorised tracking computer thing a beginner can pick up how to find some different objects in the sky without too much difficulty? (certainly the Moon I guess is pretty easy, but some of the other planets and things?)
If she has never used a scope and enjoys picking things out by eye then maybe you she would be better off with a dobsonian mount.
That 130EQ is an equatorial mount, which can be tricky to use for new beginners. Plus, the aperture is quite low.
If you can stretch to this I would highly recommend it.
http://www.firstlightoptics.com/beginner-telescopes/skywatcher-skyliner-150p-dobsonian.html
Much easier to use, more stable and will show a lot more.
The Skyliner uses an alt azimuth platform, which you just put on the floor and manually push around. They really are great telescopes.
Down the line you always buy a separate EQ mount for the Skyliner tube.
Soldato
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... Wait, is the Skyliner a lot bigger than I think it is then?
http://i.ytimg.com/vi/BDvJa0YyvMc/maxresdefault.jpg
There is a pic of the 150p Skyliner (6" primary mirror) to give you scale.
The circular part of the base rotates and the tube goes up and down, they are extremely easy and fun to use.
That scope will show the rings of Saturn, colored bands on Jupiter etc
Man of Honour
Some cool facts about our neighbourhood.
The Milky Way Galaxy is an immense and very interesting place. Not only does it measure some 100,000–120,000 light-years in diameter, it is home to planet Earth, the birthplace of humanity. Our Solar System resides roughly 27,000 light-years away from the Galactic Center, on the inner edge of one of the spiral-shaped concentrations of gas and dust particles called the Orion Arm.
But within these facts about the Milky Way lie some additional tidbits of information, all of which are sure to impress and inspire. Here are ten such facts, listed in no particular order:
1. It’s warped.
2. It has a halo, but you can’t directly see it.
3. It has over 200 billion stars
4. It’s really dusty and gassy.
5. It was made from other galaxies.
6. Every picture you’ve seen of the Milky Way from above is either another galaxy or an artist’s interpretation.
7. There is a black hole at the center.
8. It’s almost as old as the Universe itself.
9. It’s part of the Virgo Supercluster, a group of galaxies within 150 million light years.
10. It’s on the move
The Milky Way Galaxy is an immense and very interesting place. Not only does it measure some 100,000–120,000 light-years in diameter, it is home to planet Earth, the birthplace of humanity. Our Solar System resides roughly 27,000 light-years away from the Galactic Center, on the inner edge of one of the spiral-shaped concentrations of gas and dust particles called the Orion Arm.
But within these facts about the Milky Way lie some additional tidbits of information, all of which are sure to impress and inspire. Here are ten such facts, listed in no particular order:
1. It’s warped.
For starters, the Milky Way is a disk about 120,000 light years across with a central bulge that has a diameter of 12,000 light years (see the Guide to Space article for more information). The disk is far from perfectly flat though, as can be seen in the picture below. In fact, it is warped in shape, a fact which astronomers attribute to the our galaxy’s two neighbors -the Large and Small Magellanic clouds.
These two dwarf galaxies — which are part of our “Local Group” of galaxies and may be orbiting the Milky Way — are believed to have been pulling on the dark matter in our galaxy like in a game of galactic tug-of-war. The tugging creates a sort of oscillating frequency that pulls on the galaxy’s hydrogen gas, of which the Milky Way has lots of (for more information, check out How the Milky Way got its Warp).
The Spiral Galaxy ESO 510-13 is warped similar to our own. Credit: NASA/Hubble Heritage Team (STScI / AURA), C. Conselice (U. Wisconsin / STScI/ NASA
The warp of Spiral Galaxy ESO 510-13 is similar to that of our own. Credit: NASA/Hubble
These two dwarf galaxies — which are part of our “Local Group” of galaxies and may be orbiting the Milky Way — are believed to have been pulling on the dark matter in our galaxy like in a game of galactic tug-of-war. The tugging creates a sort of oscillating frequency that pulls on the galaxy’s hydrogen gas, of which the Milky Way has lots of (for more information, check out How the Milky Way got its Warp).
The Spiral Galaxy ESO 510-13 is warped similar to our own. Credit: NASA/Hubble Heritage Team (STScI / AURA), C. Conselice (U. Wisconsin / STScI/ NASA
The warp of Spiral Galaxy ESO 510-13 is similar to that of our own. Credit: NASA/Hubble
2. It has a halo, but you can’t directly see it.
Scientists believe that 90% of our galaxy’s mass consists of dark matter, which gives it a mysterious halo. That means that all of the “luminous matter” – i.e. that which we can see with the naked eye or a telescopes – makes up less than 10% of the mass of the Milky Way. Its halo is not the conventional glowing sort we tend to think of when picturing angels or observing comets.
In this case, the halo is actually invisible, but its existence has been demonstrated by running simulations of how the Milky Way would appear without this invisible mass, and how fast the stars inside our galaxy’s disk orbit the center.
The heavier the galaxy, the faster they should be orbiting. If one were to assume that the galaxy is made up only of matter that we can see, then the rotation rate would be significantly less than what we observe. Hence, the rest of that mass must be made up of an elusive, invisible mass – aka. “dark matter” – or matter that only interacts gravitationally with “normal matter”.
To see some images of the probable distribution and density of dark matter in our galaxy, check out The Via Lactea Project.
In this case, the halo is actually invisible, but its existence has been demonstrated by running simulations of how the Milky Way would appear without this invisible mass, and how fast the stars inside our galaxy’s disk orbit the center.
The heavier the galaxy, the faster they should be orbiting. If one were to assume that the galaxy is made up only of matter that we can see, then the rotation rate would be significantly less than what we observe. Hence, the rest of that mass must be made up of an elusive, invisible mass – aka. “dark matter” – or matter that only interacts gravitationally with “normal matter”.
To see some images of the probable distribution and density of dark matter in our galaxy, check out The Via Lactea Project.
3. It has over 200 billion stars
As galaxies go, the Milky Way is a middleweight. The largest galaxy we know of, which is designated IC 1101, has over 100 trillion stars, and other large galaxies can have as many as a trillion. Dwarf galaxies such as the aforementioned Large Magellanic Cloud have about 10 billion stars. The Milky Way has between 100-400 billion stars; but when you look up into the night sky, the most you can see from any one point on the globe is about 2,500. This number is not fixed, however, because the Milky Way is constantly losing stars through supernovae, and producing new ones all the time (about seven per year).
These images taken by the Spitzer Space Telescope show dust and gas concentrations around a distant supernova. Credit: NASA/JPL-Caltech
These images taken by the Spitzer Space Telescope show dust and gas concentrations around a distant supernova. Credit: NASA/JPL-Caltech
4. It’s really dusty and gassy.
Though it may not look like it to the casual observer, the Milky Way is full of dust and gas. This matter makes up a whopping 10-15% of the luminous/visible matter in our galaxy, with the remainder being the stars. Our galaxy is roughly 100,000 light years across, and we can only see about 6,000 light years into the disk in the visible spectrum. Still, when light pollution is not significant, the dusty ring of the Milky Way can be discerned in the night sky.
The thickness of the dust deflects visible light (as is explained here) but infrared light can pass through the dust, which makes infrared telescopes like the Spitzer Space Telescope extremely valuable tools in mapping and studying the galaxy. Spitzer can peer through the dust to give us extraordinarily clear views of what is going on at the heart of the galaxy and in star-forming regions.
The thickness of the dust deflects visible light (as is explained here) but infrared light can pass through the dust, which makes infrared telescopes like the Spitzer Space Telescope extremely valuable tools in mapping and studying the galaxy. Spitzer can peer through the dust to give us extraordinarily clear views of what is going on at the heart of the galaxy and in star-forming regions.
5. It was made from other galaxies.
The Milky Way wasn’t always as it is today – a beautiful, warped spiral. It became its current size and shape by eating up other galaxies, and is still doing so today. In fact, the Canis Major Dwarf Galaxy is the closest galaxy to the Milky Way because its stars are currently being added to the Milky Way’s disk. And our galaxy has consumed others in its long history, such as the Sagittarius Dwarf Galaxy.
6. Every picture you’ve seen of the Milky Way from above is either another galaxy or an artist’s interpretation.
Currently, we can’t take a picture of the Milky Way from above. This is due to the fact that we are inside the galactic disk, about 26,000 light years from the galactic center. It would be like trying to take a picture of your own house from the inside. This means that any of the beautiful pictures you’ve ever seen of a spiral galaxy that is supposedly the Milky Way is either a picture of another spiral galaxy, or the rendering of a talented artist.
Imaging the Milky Way from above is a long, long way off. However, this doesn’t mean that we can’t take breathtaking images of the Milky Way from our vantage point!
Imaging the Milky Way from above is a long, long way off. However, this doesn’t mean that we can’t take breathtaking images of the Milky Way from our vantage point!
7. There is a black hole at the center.
Most larger galaxies have a supermassive black hole (SMBH) at the center, and the Milky Way is no exception. The center of our galaxy is called Sagittarius A*, a massive source of radio waves that is believed to be a black hole that measures 22,500 kilometers (14 million miles) across – about the size of Mercury’s orbit. But this is just the black hole itself.
All of the mass trying to get into the black hole – called the accretion disk – forms a disk that has 4.6 million times the mass of our Sun and would fit inside the orbit of the Earth. Though like other black holes, Sgr A* tries to consume anything that happens to be nearby, star formation has been detected near this behemoth astronomical phenomenon.
All of the mass trying to get into the black hole – called the accretion disk – forms a disk that has 4.6 million times the mass of our Sun and would fit inside the orbit of the Earth. Though like other black holes, Sgr A* tries to consume anything that happens to be nearby, star formation has been detected near this behemoth astronomical phenomenon.
8. It’s almost as old as the Universe itself.
The most recent estimates place the age of the Universe at about 13.7 billion years. Our Milky Way has been around for about 13.6 billion of those years, give or take another 800 million. The oldest stars in our the Milky Way are found in globular clusters, and the age of our galaxy is determined by measuring the age of these stars, and then extrapolating the age of what preceded them.
Though some of the constituents of the Milky Way have been around for a long time, the disk and bulge themselves didn’t form until about 10-12 billion years ago. And that bulge may have formed earlier than the rest of the galaxy.
Though some of the constituents of the Milky Way have been around for a long time, the disk and bulge themselves didn’t form until about 10-12 billion years ago. And that bulge may have formed earlier than the rest of the galaxy.
9. It’s part of the Virgo Supercluster, a group of galaxies within 150 million light years.
As big as it is, the Milky Way is part of an even larger galactic structures. Our closest neighbors include the Large and Small Magellanic Clouds, and the Andromeda Galaxy – the closest spiral galaxy to the Milky Way. Along with some 50 other galaxies, the Milky Way and its immediate surroundings make up a cluster known as the Local Group.
And yet, this is still just a small fraction of our stellar neighborhood. Father out, we find that the Milky Way is part of an even larger grouping of galaxies known as the Virgo Supercluster. Superclusters are groupings of galaxies on very large scales that measure in the hundreds of millions of light years in diameter. In between these superclusters are large stretches of open space where intrepid explorers or space probes would encounter very little in the way of galaxies or matter.
In the case of the Virgo Supercluster, at least 100 galaxy groups and clusters are located within it massive 33 megaparsec (110 million light-year) diameter. And a 2014 study indicates that the Virgo Supercluster is only a lobe of a greater supercluster, Laniakea, which is centered on the Great Attractor.
And yet, this is still just a small fraction of our stellar neighborhood. Father out, we find that the Milky Way is part of an even larger grouping of galaxies known as the Virgo Supercluster. Superclusters are groupings of galaxies on very large scales that measure in the hundreds of millions of light years in diameter. In between these superclusters are large stretches of open space where intrepid explorers or space probes would encounter very little in the way of galaxies or matter.
In the case of the Virgo Supercluster, at least 100 galaxy groups and clusters are located within it massive 33 megaparsec (110 million light-year) diameter. And a 2014 study indicates that the Virgo Supercluster is only a lobe of a greater supercluster, Laniakea, which is centered on the Great Attractor.
10. It’s on the move
The Milky Way, along with everything else in the Universe, is moving through space. The Earth moves around the Sun, the Sun around the Milky Way, and the Milky Way as part of the Local Group, which is moving relative to the Cosmic Microwave Background (CMB) radiation – the radiation left over from the Big Bang.
The CMB is a convenient reference point to use when determining the velocity of things in the universe. Relative to the CMB, the Local Group is calculated to be moving at a speed of about 600 km/s, which works out to about 2.2 million km/h. Such speeds stagger the mind and squash any notions of moving fast within our humble, terrestrial frame of reference!
For many more facts about the Milky Way, visit the Guide to Space, listen to the Astronomy Cast episode on the Milky Way, or visit the Students for the Exploration and Development of Space at seds.org..
The CMB is a convenient reference point to use when determining the velocity of things in the universe. Relative to the CMB, the Local Group is calculated to be moving at a speed of about 600 km/s, which works out to about 2.2 million km/h. Such speeds stagger the mind and squash any notions of moving fast within our humble, terrestrial frame of reference!
For many more facts about the Milky Way, visit the Guide to Space, listen to the Astronomy Cast episode on the Milky Way, or visit the Students for the Exploration and Development of Space at seds.org..
Soldato
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Wow, okay I was way off, I was thinking the tube itself was more the size of the 130EQ making the whole unit quite little. I guess it's fairly weighty? At the moment we have the advantage that we've just moved to the in-development edge of a new-build estate and they haven't even installed street-lights yet so its very, very dark outside... but supposing eventually it gets too light around here to get as much out of the telescope at home, will something that big be quite awkward to transport to take it to places to get some good views?
I guess this will show up the fact that I'm also a complete novice, but the mount on the Dobsonian - the swivel of the base I guess is in the plane of the surface of the ground and then you have the up/down tilt of the scope, is that easier to track things with than an EQ mount? (which as I understand it allows the scope to rotate in a few directions which you align with the spin of the planet or similar..)
I guess this will show up the fact that I'm also a complete novice, but the mount on the Dobsonian - the swivel of the base I guess is in the plane of the surface of the ground and then you have the up/down tilt of the scope, is that easier to track things with than an EQ mount? (which as I understand it allows the scope to rotate in a few directions which you align with the spin of the planet or similar..)
For a beginner - the idea of a dob seems more intuitive. You plonk it down and you steer it. Dobs as large as a 76" mirror have been made so it's a very respected option (infact I'm considering making my own).
The earth rotates in an off centre so just as the sun moves in an arch, the stars also appear to follow that arc across the sky.
With an alt-az mount like a dob, you manually move the mount in both axis to track the stars/planets as they move. With an EQ mount you only need to move one axis. However you'll need to really get used to moving as the stars do to get the hang of it.
Note - it's possible to put some scope rings and add it to an EQ mount at a later stage.
Picture wise you'll get more bang for your buck with the SW 150 or 200 dob than you would with the 130 or a refractor.
Soldato
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Thanks again for the advice... I do like the idea of the SW 150 though just trying to work out where we would keep it when not in use!! I suppose it'd be okay stood in the corner of my little office room... Only other place really would be in the garage but I guess it might not be good for it to be kept out there
Any recommendations if I need to get anything specifically to go with it? I was going to grab a copy of that "Turn left at Orion" book which seems to be frequently recommended, but will she need any additional eyepieces or anything like that?
Any recommendations if I need to get anything specifically to go with it? I was going to grab a copy of that "Turn left at Orion" book which seems to be frequently recommended, but will she need any additional eyepieces or anything like that?
Man of Honour
Phases of the moon in 2015 (Northern Hemisphere), without and without annotations:
Least you could have done is given a spoiler warning! That's ruined it for all of us now
Man of Honour
2015 for the Southern hemisphere:
Man of Honour
Ode to Hubble coming up next year as part of Hubble 25 celebrations:
Man of Honour
Rosetta discovers water on comet 67p like nothing on Earth:
More:
http://www.esa.int/Our_Activities/S...etta_fuels_debate_on_origin_of_Earth_s_oceans
So it is more likely that the water came from asteroids but nothing can be ruled out.
More:
http://www.esa.int/Our_Activities/S...etta_fuels_debate_on_origin_of_Earth_s_oceans
So it is more likely that the water came from asteroids but nothing can be ruled out.
Man of Honour
Colour image of comet released today:
Comet 67P/Churyumov-Gerasimenko as it would be seen by the human eye.
More:
http://blogs.esa.int/rosetta/2014/12/12/comet-67pc-g-in-living-colour/
Comet 67P/Churyumov-Gerasimenko as it would be seen by the human eye.
More:
http://blogs.esa.int/rosetta/2014/12/12/comet-67pc-g-in-living-colour/