Galaxies are far away, it's true, but many of them are bigger than they are far, at least by comparison to the worlds within our solar system! Think about that for a moment -- how something that is millions of light-years away can still appear a thousand times bigger than something that's inside our own solar system. Here's a related question that I get asked a lot. There is a spacecraft on its way to Pluto right now, with a very sharp-eyed camera.
New Horizons is beyond Uranus' orbit now, and is closer to Pluto than it is to Earth. In fact, Pluto is just about a billion kilometers away right now, while Earth is about 4 billion kilometers away; so New Horizons is 4 times closer to Pluto than Earth is. Shouldn't New Horizons be getting pictures of Pluto that are better than Hubble's by now? Obviously we're not seeing great New Horizons pictures of Pluto yet, so the answer must be no, but you should try calculating it for yourself.
And then answer the question: when will New Horizons' pictures of Pluto be better than what we can get from Hubble? Inclined The telescope has brought light to the causes of gamma-ray bursts, how planetary collisions work , the expansion of the Universe and even hidden dark matter. The telescope is named in honour of Edwin Hubble , an astronomer who discovered many galaxies beyond our own using a telescope in California in the s.
He is often credited as the man who confirmed the Universe is expanding, a finding that was announced in But very slowly: a report from September predicts a Hubble re-entry no earlier than Though the disks only reflect visible light from the star, they glow in infrared light, which Hubble can also detect.
Astronomers are using both old and new Hubble observations to discover disks forming around other stars. These dust-disk searches reveal surprising characteristics of planet-forming disks, and no two look the same. These are not uniform flat disks; they are three-dimensional shapes with many smaller complex features. For instance, features in one ring-like system resemble a huge spray of debris from the recent collision of two objects. This small sample shows marked diversity.
Because planets form within these disks, the shapes of the disks should reflect the architectures of the forming planetary systems. The Hubble results are consistent with exoplanet observations, where planets are found arranged in orbits that are very different than those seen in our solar system. These disk surveys also yield insight into how our solar system formed and developed.
In particular, a suspected planet collision may be similar to how the Earth-Moon system or the Pluto-Charon system formed over 4 billion years ago. In those cases, collisions between planet-sized bodies cast debris that then coalesced into companion moons.
With the launch of the James Webb Space Telescope , these disk systems may be observed in more detail in the infrared, potentially revealing evidence of newly formed planets. Worlds Around Other Suns. On This Page. Hubble is helping to answer questions such as: Are there habitable planets outside our solar system? What does Hubble tell us about exoplanets? How do exoplanets form? Habitable Planets. Studying Exoplanets.
The most remote object spotted by Hubble is a galaxy called UDFj, which was spotted as a tiny speck of light in the background of a series of observations made in — heic While this result awaits spectroscopic confirmation, the astronomers who made this discovery are confident that it is the most remote object ever to be identified.
It is at a redshift of around ten, which means that the light from it has taken Firstly, galaxies have to have time to form stars after the Big Bang this takes several hundred million years before we can see them. Secondly, the young galaxies will be shrouded in large amounts of gas and dust that obscure our view of the early Universe.
Hubble currently provides the best resolution in the optical and ultraviolet UV wavelength range in the world. This is extremely important for the identification of interesting objects.
Adaptive optics techniques can be used with ground-based telescopes to obtain a similar or even superior resolution to that of Hubble, but only for small fields of view and in the infrared wavelength range. As mentioned, Hubble provides access to the ultraviolet wavelength range. The UV light is blocked by the Earth's atmosphere, so observations in the UV can only be performed from space.
They are very important for our understanding of the physical processes that take place in astronomical objects. Because it is above the Earth's atmosphere. The atmosphere disturbs the starlight a bit like looking through water and blurs the images. So Hubble's images are much sharper than those from other telescopes. Yes, it is true. During its first three years Hubble suffered from what is known as spherical aberration. Spherical aberration is an optical defect and Hubble's main mirror is two microns too flat.
The problem was caused by a faulty measuring device used during the process of polishing the mirror. Hubble has made a series of very deep observations taken in very dark parts of the sky. Like using a long exposure on a digital camera, these long exposure shots up to several weeks reveal very faint details that are not normally visible in shorter exposures.
Hubble's so-called angular resolution — or sharpness — is measured as the smallest angle on the sky that it can resolve i. Quite impressive! But Hubble would have to look down through the atmosphere, which would blur the images and make the actual resolution worse. In addition, Hubble orbits the Earth at such a rate that any image it took would be blurred by the motion. In the past Hubble was pointed towards Earth several times to calibrate some of its instruments.
JWST will not be a like-for-like replacement of Hubble. The biggest difference is that it will be optimised for observing infrared light with limited visible light capabilities , while Hubble is optimised for visible and UV light with limited infrared capabilities.
This means it will be better at looking through dust and gas clouds, which is useful for studying star formation. It will also be much better for studying highly redshifted objects, and is therefore expected to make major contributions to the study of the very early Universe. This is a bit difficult to explain in just a few sentences.
Hubble has measured the age and size of the Universe better than before by refining the value for the Hubble constant, which is related to the expansion rate of the Universe. It has also seen details which are not visible from the ground in the first galaxies.
Today we know that galaxies were formed earlier than previously thought and most scientists also believe that they evolve by colliding and merging together. There have been a few cases where Hubble has been aimed at the Moon - see here. This has to be done with the greatest care since the Moon is very bright , and is normally avoided.
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