Tuesday, July 31, 2012
Couriosity's Seven Minutes of Terror
In a similar vein to yesterday, here's a fascinating video about the upcoming landing of the Curiosity rover on Mars next Sunday. This landing is going to be the most complicated landing maneuver ever attempted by mankind, and it's going to be so far away that the time it takes the signal to get back to Earth is longer than the time the landing will take, should everything go smoothly. It also explains stuff a lot better than I can, so I'm going to stop talking now so you can watch the movie.
Monday, July 30, 2012
Riding a Rocket into Space
Have you ever wondered what it would be like to ride the space shuttle 28 miles up, then jump off and parachute back to Earth? That's essentially what the two solid rocket boosters (SRB's) on the shuttle did time and time again, and now you can vicariously experience it by watching the following video. This video is absolutely amazing. It is composed entirely of actual footage from cameras installed on the two SRB's that assisted the space shuttle into orbit. After doing their part the SRB's separate from the shuttle and parachute back to a splash-down on Earth. What's especially cool is that all the sound in this video is from the microphones on the cameras; nothing has been added in, although Skywalker Sound processed it a bit to help make it more audible.
This video brought me to tears. The majesty and grandeur of the space vistas, the views of Earth curving off into the distance, the incredible piece of human ingenuity that is the space shuttle...it's beautiful. And powerful. I hope you enjoy it as much as I did.
This video brought me to tears. The majesty and grandeur of the space vistas, the views of Earth curving off into the distance, the incredible piece of human ingenuity that is the space shuttle...it's beautiful. And powerful. I hope you enjoy it as much as I did.
Saturday, July 28, 2012
Closest Quasar
Today I have a picture of a very unique object to show you: the first quasar ever discovered. I had meant to take this picture before the transit of Venus, but the combination of poor weather and a heavy workload made it impossible. Luckily for me, Virgo was still high in the sky when I took this picture on the 11th of July.
A short note about quasars: quasars (short for quasi-stellar objects) are believed to be comparatively small accretion disks around supermassive black holes in distant galaxies. They are known as quasi-stellar objects because they appear star-like to all but the most powerful telescope due to their extremely great distances. They give off tremendous amounts of light all across the electromagnetic spectrum, from X-rays to infrared. Some also give off copious amounts of gamma rays and radio waves.
The quasar below is thought to be the closest quasar to us at 2.44 billion light-years away. Yes, that's billion with a "b". Our Milky Way galaxy is about 100,00 light-years across, so nearly 25,000 galaxies like the Milky Way could fit between this quasar and our galaxy. And that's the closest quasar to us. Most quasars are much further away, and due to their extreme luminosity are some of the farthest objects visible in the universe. This quasar, though, is likely the farthest object you could reasonably expect to see through an amateur-sized telescope.
Anyway, enough explanation. Here it is, entry 273 in the Third Cambridge Catalog of Radio Sources, 3C 273 itself!
Kindly hold all applause until the end of the blog post. I know it's not much to look at, but it's remarkable because of what it represents. With a 4-inch telescope and a CCD camera you and I can see the light from the mind-bogglingly intense region of warped space-time around a black hole with more than 800 million times the Sun's mass from over 2,440,000,000 light-years away. It's staggering to me that such a thing is even possible. Hopefully you can see why this is such an amazing picture, even if it isn't as showy as some of the ones I put up here.
3C 273 is an interesting object because it was the first quasar to have its spectrum taken (due to the fact that it is the brightest quasar in the visible light range), which helped show that it wasn't a star and was in fact very much further away than previously thought. Although we know more about quasars now than ever before, they continue to remain mysterious objects and there are many questions about them yet to be answered.
A short note about quasars: quasars (short for quasi-stellar objects) are believed to be comparatively small accretion disks around supermassive black holes in distant galaxies. They are known as quasi-stellar objects because they appear star-like to all but the most powerful telescope due to their extremely great distances. They give off tremendous amounts of light all across the electromagnetic spectrum, from X-rays to infrared. Some also give off copious amounts of gamma rays and radio waves.
The quasar below is thought to be the closest quasar to us at 2.44 billion light-years away. Yes, that's billion with a "b". Our Milky Way galaxy is about 100,00 light-years across, so nearly 25,000 galaxies like the Milky Way could fit between this quasar and our galaxy. And that's the closest quasar to us. Most quasars are much further away, and due to their extreme luminosity are some of the farthest objects visible in the universe. This quasar, though, is likely the farthest object you could reasonably expect to see through an amateur-sized telescope.
Anyway, enough explanation. Here it is, entry 273 in the Third Cambridge Catalog of Radio Sources, 3C 273 itself!
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| 3C 274, the closest quasar to us. Located 2.44 billion light years away in the constellation Virgo. |
Kindly hold all applause until the end of the blog post. I know it's not much to look at, but it's remarkable because of what it represents. With a 4-inch telescope and a CCD camera you and I can see the light from the mind-bogglingly intense region of warped space-time around a black hole with more than 800 million times the Sun's mass from over 2,440,000,000 light-years away. It's staggering to me that such a thing is even possible. Hopefully you can see why this is such an amazing picture, even if it isn't as showy as some of the ones I put up here.
3C 273 is an interesting object because it was the first quasar to have its spectrum taken (due to the fact that it is the brightest quasar in the visible light range), which helped show that it wasn't a star and was in fact very much further away than previously thought. Although we know more about quasars now than ever before, they continue to remain mysterious objects and there are many questions about them yet to be answered.
Thursday, July 26, 2012
Nebulous Comparisons
My post yesterday comparing the Lagoon and Orion Nebulae got me to thinking: how would they look compared to each other? I can say that the Lagoon Nebula (Messier 8) is about 110 light-years across while the Orion Nebula (Messier 42) is only 24, but those are just numbers. Being the visual person I am, I decided to see what they would actually look like if compared. So this afternoon I sat down and put together the two pictures seen below.
This picture shows the two nebulae side-by-side just as they appear on the sky:
These two nebulae are the biggest and brightest on the sky, and pretty much the only ones that can really be seen with the naked eye. The Orion Nebula looks a little bigger here due to its much closer distance (the Lagoon Nebula is about two-and-a-half times further away). Also note the difference in star density between the two pictures.
This next picture shows what they would look like if M42 was was at the distance of M8:
Quite the difference, no? To be more realistic I should also have dimmed M42 by about 7 times to accurately reflect how it would look being ~2.5 times further away, but my first attempt at a rough approximation made M42 so dim it could barely be seen. I opted instead for the slightly-less-realistic but more visually interesting picture.
As I mentioned in my last post, despite their differences M8 and M42 are more similar than not. Both are star-forming regions, both are large cavities of gas (mostly hydrogen and helium) and dust being blown open from the inside by young stars, both would probably appear boring and dark from the other side. The main differences are their size, as seen, and their location: M8 is situated nearly directly towards the galactic core from us, while M42 is located almost directly away. That's why there are a lot more stars visible around M8 than around M42.
This picture shows the two nebulae side-by-side just as they appear on the sky:
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| Left: M8, the Lagoon Nebula. Right: M42, the Orion Nebula. North is up in both pictures. |
This next picture shows what they would look like if M42 was was at the distance of M8:
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| M8 and M42 as they would be if they were the same distance away. |
As I mentioned in my last post, despite their differences M8 and M42 are more similar than not. Both are star-forming regions, both are large cavities of gas (mostly hydrogen and helium) and dust being blown open from the inside by young stars, both would probably appear boring and dark from the other side. The main differences are their size, as seen, and their location: M8 is situated nearly directly towards the galactic core from us, while M42 is located almost directly away. That's why there are a lot more stars visible around M8 than around M42.
Wednesday, July 25, 2012
Celestial Lagoons
Today I have a picture of the Lagoon Nebula, a lovely star-forming region in Sagittarius. It is similar in nature to the famous Orion Nebula and is similarly visible, very faintly, to the unaided eye. It is over five times larger than the Orion Nebula (110 light-years across vs. 24), but appears slightly smaller on the sky due to its greater distance (3,000-4,000 light-years away, compared to ~1,300 for Orion).
Like the Orion Nebula, the reddish color comes from hydrogen ionized by hot, massive young stars embedded in the nebula. The blue color comes from light scattering off dust in the cloud, similar to the way air molecules scattering light causes the sky to look blue.
The Lagoon Nebula is also similar to the Orion Nebula in that they both offer looks into the cavernous interiors of gigantic clouds of cool gas and dust. From the outside these clouds appear dark and boring, and you can see that slightly around the edges of the nebula. But when young stars inside them blow away the gas around them and offer a view inside, the sight is spectacular. Not unlike geodes, now that I think about it. (Geodes, for those who don't know, are rocks that look like any other rock on the outside to the untrained eye, but which contain beautiful crystal formations on the inside if broken apart.)
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| Messier 8, the Lagoon Nebula in Sagittarius. |
The Lagoon Nebula is also similar to the Orion Nebula in that they both offer looks into the cavernous interiors of gigantic clouds of cool gas and dust. From the outside these clouds appear dark and boring, and you can see that slightly around the edges of the nebula. But when young stars inside them blow away the gas around them and offer a view inside, the sight is spectacular. Not unlike geodes, now that I think about it. (Geodes, for those who don't know, are rocks that look like any other rock on the outside to the untrained eye, but which contain beautiful crystal formations on the inside if broken apart.)
Tuesday, July 17, 2012
Image Stretch and the Effects Thereof
Today I just want to briefly discuss a very important decision that went into making the transit of Venus video I posted last time. That decision was how to stretch the images from the CCD camera. You see, the CCD camera has a wide range of sensitivity, with 65,536 different light levels it can record. Most monitors cannot display anywhere near this amount of contrast, so the image has to have that range compressed down into what the monitor can display. In theory, this means that a lot of detail is going to be lost, and that's where stretching comes into play.
Stretching an image's histogram basically means reassigning how the compression takes place. When you're looking at an astrophoto, you may have 65,536 different levels of brightness, but a large number of those are probably going to be so close to black as no matter. You can then adjust the stretch so that they simply display as black, leaving more of the dynamic range of the monitor available for seeing detail in the brighter regions. Essentially, the image stretch lets you decide which regions of the image you want to see detail in based on their brightness.
To illustrate how important the stretch is, let me give you some examples. Immediately upon applying the reduction process to one of the images of the transit and importing it into GIMP, we get this picture:
To the left you can see the Sun with Venus in front of it and a few sunspots visible near the middle of the disk. On the right you can see the default linear stretch currently applied to the image. Basically, it maps a zero value in the image to black, a value of 65,535 to white, and linearly compresses everything in between. The horizontal scale is the brightness levels of the original image, the vertical scale is the brightness levels on the monitor, and the gray lines are a histogram representing how many pixels there are at each brightness level. What it tells us is that this image has a lot of very dark pixels (on the left, all the background), a lot of very bright pixels (on the right, the center of the Sun's disk) and a moderate number in between (around the edge of the Sun, and things like sunspots).
Speaking of sunspots, I quickly discovered that there were more than could be seen with just the default linear stretch. By cutting off the left end of the histogram pretty dramatically with another linear stretch, I could bring out details as yet unseen:
In some ways, this worked quite well – sunspots had much better definition, and you could see more of them. The main problem to me was that it made the outside edge of the Sun look a bit grainy. I ultimately decided that it was not quite good enough, and continued looking for a suitable stretch. My next attempt, which I'm calling an “exponential” stretch, looked like this:
This stretch is similar to the previous linear stretch, but leaves more detail in the dark areas. Again, the sunspots looked good, but it looked even worse around the edges than before. After playing around with variations on both of these (plus several others), I finally came up with the curve that I would end up using:
This curve is, ultimately, a compromise. It doesn't show the sunspots quite as well as either of the previous curves, but it looks much better along the edges (at least it does at 100% magnification, they all look about the same in these pictures). It took me quite a while to decide on this curve, because I'd keep looking at it and tweaking it and trying to get the absolute best curve possible, especially since I was going to be applying it to the next one hundred and eighty-seven images and didn't want to have to go back and redo it. It wasn't a decision lightly made, I'll say that much.
I also see that, having sat down to write a “brief” blog post, I managed to write a 650-word essay. I don't know why that always seems to happen. I hope you at least found it interesting. I've come to appreciate the image stretch more and more as I (hopefully) get better as an astrophotographer, and it should show in some of my upcoming pictures. A hui hou!
Stretching an image's histogram basically means reassigning how the compression takes place. When you're looking at an astrophoto, you may have 65,536 different levels of brightness, but a large number of those are probably going to be so close to black as no matter. You can then adjust the stretch so that they simply display as black, leaving more of the dynamic range of the monitor available for seeing detail in the brighter regions. Essentially, the image stretch lets you decide which regions of the image you want to see detail in based on their brightness.
To illustrate how important the stretch is, let me give you some examples. Immediately upon applying the reduction process to one of the images of the transit and importing it into GIMP, we get this picture:
To the left you can see the Sun with Venus in front of it and a few sunspots visible near the middle of the disk. On the right you can see the default linear stretch currently applied to the image. Basically, it maps a zero value in the image to black, a value of 65,535 to white, and linearly compresses everything in between. The horizontal scale is the brightness levels of the original image, the vertical scale is the brightness levels on the monitor, and the gray lines are a histogram representing how many pixels there are at each brightness level. What it tells us is that this image has a lot of very dark pixels (on the left, all the background), a lot of very bright pixels (on the right, the center of the Sun's disk) and a moderate number in between (around the edge of the Sun, and things like sunspots).
Speaking of sunspots, I quickly discovered that there were more than could be seen with just the default linear stretch. By cutting off the left end of the histogram pretty dramatically with another linear stretch, I could bring out details as yet unseen:
In some ways, this worked quite well – sunspots had much better definition, and you could see more of them. The main problem to me was that it made the outside edge of the Sun look a bit grainy. I ultimately decided that it was not quite good enough, and continued looking for a suitable stretch. My next attempt, which I'm calling an “exponential” stretch, looked like this:
This stretch is similar to the previous linear stretch, but leaves more detail in the dark areas. Again, the sunspots looked good, but it looked even worse around the edges than before. After playing around with variations on both of these (plus several others), I finally came up with the curve that I would end up using:
This curve is, ultimately, a compromise. It doesn't show the sunspots quite as well as either of the previous curves, but it looks much better along the edges (at least it does at 100% magnification, they all look about the same in these pictures). It took me quite a while to decide on this curve, because I'd keep looking at it and tweaking it and trying to get the absolute best curve possible, especially since I was going to be applying it to the next one hundred and eighty-seven images and didn't want to have to go back and redo it. It wasn't a decision lightly made, I'll say that much.
I also see that, having sat down to write a “brief” blog post, I managed to write a 650-word essay. I don't know why that always seems to happen. I hope you at least found it interesting. I've come to appreciate the image stretch more and more as I (hopefully) get better as an astrophotographer, and it should show in some of my upcoming pictures. A hui hou!
Sunday, July 15, 2012
Transit of Venus Video (At Long Last!)
Well, I have finally recovered enough from the wonderful back-to-back combination of virulent head-cold and raging sunburn to finish my long-promised video of the transit of Venus. And it only took me over a month.
First, a quick explanation: this video does not show the beginning or end of the transit. The beginning I didn't catch because I had other duties to attend to which prevented me from getting set up in time, and when I finally did I had some unexpected problems focusing. Because of this, the video doesn't start until 2:26 PM, almost two and a half hours after the transit started. The ended wasn't captured because it wasn't visible from my location, as the Sun set behind hills to west. The last frame I captured was at 6:00 PM, about 40 minutes before the transit ended. In between I took a shot every minute, for a total of 188 frames. With that said, enjoy.
Edit (1/13/2018): Remaking and re-releasing videos seems to be all the rage these days, so I thought I'd join the fun! Actually, I was reminded of this video a while back and after watching it was dissatisfied with the quality—this was years before I started seriously pursuing video editing, and was made in Windows Movie Maker. Plus now that I've got a YouTube channel it can reside there instead of relying on Blogger's somewhat shaky video hosting abilities.
First, a quick explanation: this video does not show the beginning or end of the transit. The beginning I didn't catch because I had other duties to attend to which prevented me from getting set up in time, and when I finally did I had some unexpected problems focusing. Because of this, the video doesn't start until 2:26 PM, almost two and a half hours after the transit started. The ended wasn't captured because it wasn't visible from my location, as the Sun set behind hills to west. The last frame I captured was at 6:00 PM, about 40 minutes before the transit ended. In between I took a shot every minute, for a total of 188 frames. With that said, enjoy.
Edit (1/13/2018): Remaking and re-releasing videos seems to be all the rage these days, so I thought I'd join the fun! Actually, I was reminded of this video a while back and after watching it was dissatisfied with the quality—this was years before I started seriously pursuing video editing, and was made in Windows Movie Maker. Plus now that I've got a YouTube channel it can reside there instead of relying on Blogger's somewhat shaky video hosting abilities.
Wednesday, July 11, 2012
Android Upgrades
Back in January I mentioned getting a new phone for the first time in a few years, my first smart phone to boot. My particular model (the Samsung Galaxy S II Skyrocket) was running version 2.3 of the Android operating system (codename "Gingerbread"), but was slated to get an upgrade to the shiny new version 4.0 (codename "Ice Cream Sandwich") sometime this year. There wasn't a specific date, just that it would happen during 2012. Since new versions tend to be better in most ways than old ones, you can understand that I was pretty excited about it. Well, today finally turned out to be the long-awaited upgrade day.
I followed the instructions, downloading the update and watching it install with no problems, until my phone suddenly froze after restarting on the "Updating Android" screen. After that I couldn't get it to do anything except restart, whereupon it froze thereafter at the main loading screen.
This turn of events left me a bit flustered, in a state of mind I would imagine is a less extreme version of the reaction to finding a friend in a coma (the physical shell is there, but the mind is gone). Thankfully, the friendly and helpful people at the local AT&T store were able to reset it out of its infinite loop and get it going again. From what I've seen so far my important data survived (apps I can always download again), and the best part is that it somehow managed to successfully install Ice Cream Sandwhich through it all! I haven't had much chance to play around with it yet, but it seems pretty neat from what I've seen so far.
Also, the guy at the AT&T store who was a self-proclaimed non-Adroid expert now knows the proper procedure for reseting an Android phone thanks to needing to look it up for me, so I figure I did my part for the community for the next person to come in with that particular problem.
P.S. I'm now almost completely over my sunburn and actually feeling motivated to do things again, so expect some more posts in the coming week.
I followed the instructions, downloading the update and watching it install with no problems, until my phone suddenly froze after restarting on the "Updating Android" screen. After that I couldn't get it to do anything except restart, whereupon it froze thereafter at the main loading screen.
This turn of events left me a bit flustered, in a state of mind I would imagine is a less extreme version of the reaction to finding a friend in a coma (the physical shell is there, but the mind is gone). Thankfully, the friendly and helpful people at the local AT&T store were able to reset it out of its infinite loop and get it going again. From what I've seen so far my important data survived (apps I can always download again), and the best part is that it somehow managed to successfully install Ice Cream Sandwhich through it all! I haven't had much chance to play around with it yet, but it seems pretty neat from what I've seen so far.
Also, the guy at the AT&T store who was a self-proclaimed non-Adroid expert now knows the proper procedure for reseting an Android phone thanks to needing to look it up for me, so I figure I did my part for the community for the next person to come in with that particular problem.
P.S. I'm now almost completely over my sunburn and actually feeling motivated to do things again, so expect some more posts in the coming week.
Friday, July 6, 2012
Serious Sunburn
So, you've probably noticed a distinct lack of video on this blog yesterday. I didn't forget about it, but the massive sunburn I acquired at the beach on the 4th has left me with greatly diminished motivation for doing much besides “lie around and try not to hurt too badly”. If I actually show signs of starting to heal in the next few days, I'll try to get it out sometime over the weekend. A hui hou!
Wednesday, July 4, 2012
Happy 4th of July!
I've been pretty quiet this last week on my blog, partly because I was still recovering, but also because I've been busy working on a timelapse video of the transit of Venus. It's not ready for viewing yet, but it is very nearly there. I finally finished reducing every individual frame, and just need to compile them into a workable video. (And it only took me a month...)
I'm heading off to the beach on Kona-side today (my first true “beach day” in almost three years of living here), but the video will be up tomorrow!
I'm heading off to the beach on Kona-side today (my first true “beach day” in almost three years of living here), but the video will be up tomorrow!
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