What is the possibility of finding an Earth-like planet?
The answer entirely hinges on how similar the “Earth-like” planet really has to be to Earth.If it’s enough that it has more or less the same size, gravity and surface temperature, then we already know of a few candidates like this.If you’re talking about a planet with an atmosphere so similar to ours that a normal human could survive on its surface without a space suite, and only need to use oxygen supplements for breathing, then you’re probably looking at only several decade to a century out. Getting there in a reasonable time would be the real challenge.However, if you want the planet to also have oxygen, which almost certainly requires some form of indigenous chlorophyll-laden plant-like life, then you might have to wait a lot longer than that. I won’t hazard a guess as to how long that might take.And finally, if you want a planet with indigenous animals you could hunt and eat - the answer is probably never. It’s more likely we’d be able to have a pleasant conversation with these inhabitants than eat them, since their biological make-up will almost certainly be very different from ours, and completely incompatible with the biochemistry of our digestive system.Having said all that, it’s quite likely that our Universe is infinite (i.e. I’m not limiting myself just to the “observable universe”), and as they say “ever” is a very long time…[Image: Performance Art]
Is amateur astronomy expensive to get into? How expensive of a telescope do you need to comfortably observe planetary bodies?
This will give you a little bit of an idea. It’s more about how much time you put into it and what your expectations are about being able to see planetary bodies than it is about cost. If you can’t spare a thousand dollars, there are some telescopes for less, but it will be up to you to use them well.Before you even think about buying a telescope, get a good book about amateur astronomy and go to several star parties. That will give you a very good idea what looking through different telescopes is like.I am going to try to give you realistic expectations, but I think the first picture is misleading. It happens to be a very lucky shot and is used by the manufacturer to show off his telescope. Pay particular attention to the videos to get the best idea of what it is really like.Mars, on an extremely good night, with a 6 inch Celestron. Image has been processed and sharpened. Under $1000 for telescope, camera $500Mars with an 8 inch telescope under $2000Mars in a 10 inch telescope (Dobsonian under $1500)Mars with a 7 inch and a 17.5 inch telescope. Images have been processed and sharpened. They are lucky shots under excellent seeing conditions. There are two ratings here: Seeing, which is a measurement of atmospheric turbulence. For an optical scientist, the “seeing” is characterized as “r-naught” also known as the Fried parameter. The second number is the “transparency” which optical scientists characterize as the “extinction.”17.5 inch Dobsonian. Under $10,000 but a lot of do-it-yourself work.You can spend from a few hundred dollars to tens of thousands. Here is a picture my friend Bob Fugate took from his backyard. He clearly has about $15,000 in his gear from the descriptions he gives. I haven’t asked him directly how much he has spent. He has a special filter on loan that was used to beat down the light pollution to get a great picture. As former head of the Starfire Optical Range at the Air Force, he has a little easier time borrowing filters than I do.I have shown my photo of the eclipse in 2017 on Quora but have you seen one of the Moon dark side illuminated with Earth shine? Here is an extreme HDR photo by Bob.
Do we know any star with rings like Saturn?
That depends on how much “like Saturn” you want them to be.Saturn’s rings are made up of orbiting chunks of, mostly, ice. The ice remains solid rather than subliming because it is very cold. Anything comparably close to a star would be rather warm and the ice would sublime to vapour. But you could have a disk of rocky fragments. Would you count that as “like Saturn”?Saturn’s rings are astonishingly thin compared to their radius. Amazingly thin. That turns out to be because of tidal effects from Saturn’s equatorial bulge. Those effects are very strong because the rings are rather close to Saturn and because Saturn has a significant equatorial bulge. The latter is because Saturn rotates rather fast. A ring of junk orbiting a star would likely be further out, and stars’ equatorial bulges are usually not as significant as Saturn’s. If a star had a debris disk that was distinctly ring-shaped but not as fantastically thin as Saturn’s rings, would you count that?Those things said, we have found at least 900 stars that have a debris disk.
Why do astronomers consider the Orion Nebula important?
Stars typically form in clouds of dust and gas, and it is common for multiple stars to form at different places in the cloud. (Think of shaking up a "snow globe" and then freezing the picture - each tiny snowflake might be the location of a nascent star and a planetary system.)The Orion Nebula is one such cloud, and at 1500 light-years away it is close enough to allow telescopes like the Hubble Space Telescope to examine it in great detail. Several new stars in the cloud (a group called the "trapezium") light it up from the inside, allowing us to see it even with the naked eye from Earth. (Imagine going into a completely dark room in which people had been smoking, and then turning on a single, hanging light bulb. You would immediately notice the traces of smoke all around. This is what allows us to see the cloud, with the stars of the trapezium serving as the "naked light bulb").Hubble has been able to identify numerous locations in the cloud where stars and their associated planetary systems are forming. There's an IMAX movie that shows a lot of this detail. The link above will let you view it on YouTube.And last but not least, it's absolutely beautiful to observe in anything from binoculars up to the largest amateur scopes.
What evidence do we have that star formation is happening right now in the Orion Nebula?
Well, In the middle portion of that nebula, Scientists have found four luminous stars are forming.... all which are in protostar age with protoplanetary disks around them, They can be seen arranged in a trapezium like structure, So they all together are called Trapezium in orion.... I am pasting here info about them which i have copied from a site. Trapezium(orion) A star cluster at the heart of the Orion Nebula consisting of more than 1,000 young stars crowded into a space about four light-years in diameter (roughly the distance between the Sun and the next nearest star). A few of these stars are hot O and B stars ; however, the majority are later-type, cooler, less luminous and less massive pre-main sequence stars of a solar mass or less. With an average stellar age of only one million years, the Trapezium is one of the youngest clusters known. Most of its member stars are hidden by dust or by the glare of the nebula but are visible at infrared wavelengths. The four brightest stars (A, B, C, and D), which form the vertices of a trapezium and give the cluster its name, can be seen easily with a small telescope. Two fainter stars of eleventh magnitude, E and F, show up in moderately sized amateur instruments under good seeing conditions. A further two, of sixteenth magnitude, G and H, are only visible in very large amateur scopes. Theta1 Orionis A, also known as V1016, is an eclipsing binary with a period of 65.432 days and a magnitude range of 6.72 to 7.65. Theta1 B, also known as BM Orionis, is another eclipsing binary, spectral type B2-B3, with a period of 6.471 days and a magnitude range of 7.90 to 8.65. An infrared companion has also been discovered in the Theta1 A system, making it a triple star, and Theta1 B is now known to be a quadruple system, with three components detected separately in the near-infrared. Infrared observations have that shown Theta1 C, which is actually the brightest star in the cluster, is a close binary as well.
Why do we have such great color images of galaxies that are hundreds of thousands of light years away, yet have terrible images of stars that are in the tens of light years away?
There’s a few things that have been touched on in other answers but I’ll just see if I can flush it out a bit more. First off, galaxies are massive, and it’s the collective light of the stars in them that give the color we see… typically bluish in areas that are younger and have more star growth and yellowish in older parts (usually the core). Closer galaxies such as M31 and M33 can show more colors as we can actually resolve detail of some of the large nebula clouds in them. On the other hand stars are tiny compared to the size of galaxies… our galaxy is approximately 100,000 light years across, where as our sun, in the same terminology is about about 4.6 light seconds in diameter.That being said, we have actually imaged the disc of a few stars as well as protoplanetary discs around young stars. The thing is stars themselves aren’t that terribly colorful, the color of a star is mainly dictated by the temperature, red stars are cooler while blue stars are hotter, with white falling in-between, but it’s one uniform color across the surface. While it’s amazing to be able to see the disc of another star, or the dust around it, it doesn’t have that same visual impact that a galaxy has, and that’s why you don’t see many images of them. And to take it one step further, on June 2nd, 2018, the VLT captured the image of a new born planet… VLT Captures First Confirmed Image of Newborn Planet PDS 70b. Simply amazing, but to look at the planet itself, doesn’t look like much, until you put it in perspective.