What is Hubble: Definition and 275 Discussions

The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versatile, renowned both as a vital research tool and as a public relations boon for astronomy. The Hubble telescope is named after astronomer Edwin Hubble and is one of NASA's Great Observatories, along with the Compton Gamma Ray Observatory (1991–2000), the Chandra X-ray Observatory, and the Spitzer Space Telescope (2003–2020). At the time of its launch in 1990, the Hubble Space Telescope cost $4.7 billion (equivalent to $9,310,200,000 in 2020).
Hubble features a 2.4 m (7 ft 10 in) mirror, and its four main instruments observe in the ultraviolet, visible, and near-infrared regions of the electromagnetic spectrum. Hubble's orbit outside the distortion of atmosphere of Earth allows it to capture extremely high-resolution images with substantially lower background light than ground-based telescopes. It has recorded some of the most detailed visible light images, allowing a deep view into space. Many Hubble observations have led to breakthroughs in astrophysics, such as determining the rate of expansion of the universe.
The Hubble telescope was built by the United States space agency NASA with contributions from the European Space Agency. The Space Telescope Science Institute (STScI) selects Hubble's targets and processes the resulting data, while the Goddard Space Flight Center (GSFC) controls the spacecraft. Space telescopes were proposed as early as 1923. Hubble was funded in the 1970s with a proposed launch in 1983, but the project was beset by technical delays, budget problems, and the 1986 Challenger disaster. It was finally launched by Discovery in 1990, but its main mirror had been ground incorrectly, resulting in spherical aberration that compromised the telescope's capabilities. The optics were corrected to their intended quality by a servicing mission in 1993.
Hubble is the only telescope designed to be maintained in space by astronauts. Five Space Shuttle missions have repaired, upgraded, and replaced systems on the telescope, including all five of the main instruments. The fifth mission was initially canceled on safety grounds following the Columbia disaster (2003), but NASA administrator Michael D. Griffin approved the fifth servicing mission which was completed in 2009. The telescope completed 30 years in operation in April 2020 and could last until 2030–2040. One successor to the Hubble telescope is the James Webb Space Telescope (JWST) which is scheduled to be launched in late 2021.

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  1. C

    Hubble redshift and calculation of galactic rotation curves

    I am interested in whether it is necessary to account for the effects of the Hubble Redshift in determining the rotation velocities of galaxies exhibiting keplerian motion and, in particular, whether the associated spatial expansion of the Universe is known to result in spectral shifts that...
  2. Jimster41

    Hubble constant and Entropy v2

    Is there agreement here regarding the relationship between expansion of the universe from its initial conditions, entropy (2nd law), time, (and more tenuously perhaps) "evolution"? I asked a question awhile back that was too specific I think that tried to tie the constant of expansion to the...
  3. A

    Prove evolution of Hubble parameter

    Homework Statement Prove that Homework Equations [/B]The Attempt at a Solution Without cosmological constant, one finds that where w is the ratio between pressure and density.[/B]
  4. P

    Does the Hubble Parameter Go to Zero as the Universe Expands Forever?

    I recently came across this claim: "On the other hand, in certain cases even an expanding cosmology may have 0 average expansion, due to the fact that we are averaging over an infinite amount of time. " Is this correct? can someone explain how averaging over infinity time leads to zero ...
  5. Jimster41

    Is the Hubble Constant Linked to the Second Law of Thermodynamics?

    Do I understand correctly (in general terms) or wildly incorrectly if I imagine that the constant of expansion and the second law of thermodynamics are very closely connected, or even that the constant of expansion is potentially the source of the second law?
  6. Andy Resnick

    Is the Hubble Telescope Smiling at a Gravitational Lens?

    Story at: http://spaceref.com/astronomy/hubble-sees-a-smiling-gravitational-lens.html
  7. P

    Velocity of receding galaxies. Hubble <-> scale factor

    Hi there, This is my first post but I've been a spectator for a long time now. So I've been working on some of the basics of cosmic expansion and there is one contradiction that I came upon that I can't seem to resolve. I've looked around some of the similar threads but I couldn't find anything...
  8. Ganesh Ujwal

    Accumulated environmental damage to Hubble main mirror

    I'm interested in understanding what effect does long-term radiation and microdust exposure would do to the surface roughness of a high-precision mirror like the one on the Hubble. Since it has been on orbit for 24 years, it provides an unique opportunity to estimate accumulated environmental...
  9. S

    Observational data for evolution of Hubble rate

    Is there any observational data available for evolution of Hubble rate? To give some context, read the dark energy FAQ by Sean Caroll here. He says: "If the universe is decelerating, the Hubble constant is decreasing. If the Hubble constant is increasing, the universe is accelerating. But...
  10. gangula pranav

    Is the Universe Heading Towards a Big Crunch or Eternal Expansion?

    if the speed of the expansion is decreasing then it would mean that the radius of the Hubble sphere is increasing because it would require more space to expand faster than the speed of light .but as you said if the speed of expansion is increasing then why is the Hubble sphere increasing and why...
  11. gangula pranav

    Exploring the Hubble Sphere & Hubble Constant

    why does the Hubble sphere increase amd why is the Hubble constant called a constant if the value keeps changing.
  12. G

    Expanding Universe: Verifying Space Expansion Through Galaxies

    How one can say that the space is expanding by just verifying that the galaxies are speeding away from each other?
  13. 2

    What exactly is the Hubble parameter?

    I'm looking at general relativity and particularly considering what happens at the Big Bang. I think the Friedman equation is H^2=\frac{8\pi G}{3}\rho so I see that as the matter density goes to infinity, H goes to infinity. According to this video (around 10:10), this is where the problem lies...
  14. L

    Time derivative of Hubble parameter

    Is rather a question of calculus skills, but how do I get the time derivative of the Hubble parameter here in [1]? Is it the Leibnitz rule, the chain rule, some clever re-arrangement? thank you
  15. C

    Hubble Finds Vast Reservoir of Gas Near Milky Way

    by Dr. Ken Croswell, author of The Alchemy of the Heavens The Milky Way may have found a solution to its gas shortage. Astronomers had calculated that our home galaxy possesses only enough fuel to forge new stars for just a few billion more years. But scientists have now discovered that a...
  16. L

    Light Cone - Hubble Radius & Time T and R Relationship

    T (Gy) R (Gly) 0.00037338 0.00062840 0.00249614 0.00395626 0.01530893 0.02347787 0.09015807 0.13632116 0.52234170 0.78510382 2.97769059 4.37361531 13.78720586 14.39993199 32.88494318 17.18490043 47.72506282 17.29112724 62.59805320...
  17. marcus

    Concordance value of Hubble growth rate (2014)

    There has been a flood of new data. Cosmologists have not yet settled on a new agreed value of H0. This may help lead to one. http://arxiv.org/abs/1406.1718 The 1% Concordance Hubble Constant C. L. Bennett (1), D. Larson (1), J. L. Weiland (1), G. Hinshaw (2) ((1) Johns Hopkins University, (2)...
  18. M

    Hubble's Law and Acceleration: Are Distant Objects Accelerating Away from Us?

    Hubble’s law tells us that the velocity of distant objects increases with distance as v = Hr. Does this mean that the farther a distant object gets the more rapidly that object will recede away from us? That is, are these distant objects accelerating away from us? Can we say v = Hr, and so...
  19. marcus

    Calculating critical density of mass, from Hubble time, for exercise

    Jorrie's calculator (Lightcone) makes cosmic history tables which tell you among other things the Hubble times in past years. For convenience let's temporarily use greek Theta Θ to stand for THubble so we don't have to write so much. Basic facts (definitions actually) are that Θ = 1/H and the...
  20. P

    Gravitational Redshift and Hubble.

    Hey guys, I feel like an idiot for asking this. However, I wanted to make sure that my head was screwed on straight before I asked my old astronomy professor permission to use some of his old lecture notes. Is gravitational redshift one of the causes of Hubble's Law? Is the Redshift of the...
  21. V

    Energy scale of Hubble constant for dark energy scalar field

    Hello All, In Carroll's there is a brief introduction to a dynamical dark energy in which the equation of motion for slowly rolling scalar field is discussed. Then to give an idea about the mass scale of this field it is compared to the Hubble constant, saying that it has an energy of...
  22. C

    Hubble Telescope: What's the Big Flap/Door?

    I did a cursory search on the forum, and I browsed Wiki...but maybe I missed it. What is that big Flap/Door on the end of the scope.? Is it part of the optics, or is it a protection device, or a...? Thank You
  23. tomwilliam2

    Variation of Hubble constant in model universe

    Homework Statement For a problem I'm doing, I am considering a universe in which k=0, and I'm told that I can consider most of the expansion to have happened during a phase when only one of the density parameters was dominant (I know which one, as well), but I don't know the scale factor or...
  24. Greg Bernhardt

    Hubble Picture Crushes Your Sense of Scale

    Hubble Sees Infant Galaxies at the Edge of the Universe http://www.slate.com/blogs/bad_astronomy/2014/01/09/distant_galaxies_hubble_image_of_galaxies_at_the_universe_s_edge.html
  25. T

    How Does the Integral's Limit Affect the Dark Energy Density Equation?

    Hello! This is my first post, so go easy on me! I'm working through Scott Dodelson's book Modern Cosmology http://books.google.com/books?id=3oPRxdXJexcC&pg=PA23&source=gbs_toc_r&cad=4#v=onepage&q&f=false and I am a bit confused about equation 2.85: $$\rho_{DE} \propto e^{-3 \int^a...
  26. H

    Is the Critical Density Related to the Friedmann Equation?

    Homework Statement For a κ=0 universe with no cosmological constant, show that H(z)=H0(1+z)3/2 Homework Equations Friedmann equation: H2=\frac{8*\pi*g}{3c^2}-\frac{κc^2}{r^2}*\frac{1}{a(t)^2} The Attempt at a Solution I know that R(z)=R0/(1+z) but I do not know where this comes...
  27. E

    Hubble constant from Time delays

    Hello, everyone it seems to me that people understand how to do this problem but I am struggling to solve it. Homework Statement A quasar with redshift 0.3 is gravitationally lensed into two images by an elliptical galaxy at redshift 0.18. There are two images of the quasar which are separated...
  28. H

    Stargazing How deep can Hubble Telescope see?

    How deep can Hubble Telescope see?? -I understand that the Hubble telescope can only resolve galaxies at about 13 billion years old, using gravitational lensing. I am curious, is this because the telescope does not have the power to see farther? Or is this because there are no farther...
  29. Greg Bernhardt

    Stargazing Hubble telescope finds a planet where it rains glass

    http://www.cnn.com/2013/07/11/world/space-blue-planet/index.html?hpt=hp_t1
  30. F

    The cosmological Big Rip and a shrinking hubble radius

    The cosmological "Big Rip" and a shrinking Hubble radius Doesn't an expanding universe forecast such outcomes as a faded and unobservable cmb, galaxies moving away from each other greater than the speed of light, a gravitationally unbound solar system, and eventually an observable universe...
  31. Q

    Confusion about the accelerating expansion of the universe and Hubble

    My school textbook says that discovery of the 1a supernova was what led to the understanding that the universe expansion is accelerating but doesn't hubble's equation already suggest that the universe would expand at an accelerating rate? V = Hd (V = velocity, H = hubble's constant, d =...
  32. C

    Did Hubble opine that the universe was expanding?

    When Hubble published that the galaxies were moving away from each other, the further away the greater redshift and the greater separation velocity, was he saying that space itself was expanding, on the basis of Einstein's general theory, or was he assuming a more or less fixed space, with...
  33. marcus

    How to derive dark energy density from Jorrie's Hubble radius limit

    How to derive "dark energy" density from Jorrie's Hubble radius limit (c^4/(8 pi G))*3*(17.3e9 light years)^(-2) Paste that in the google window, and see what you get. When I paste that into google I get 0.5393 nanopascal, which is equivalent to 0.5393 nanojoule per cubic meter. If the...
  34. N

    Stargazing Pictures from the Hubble Space Telescope

    78 Pictures from the Hubble Space Telescope http://www.space.com/15235-hubble-space-telescope-latest-photos.html
  35. L

    Hubble Constant am I gettting this right?

    Hi guys, I am in a state of slight confusion! I need to know if I am getting this information right, or I have gotten something wrong somewhere! It is to do with the Hubble constant and the Hubble law. So 1920 Edwin Hubble estimated that the Universe was 14 Billion years Old but new...
  36. P

    Redshift at 11.9 and the Hubble Constant

    Recently, astronomers from Caltech and Edinburgh University discovered galaxies with a redshift of 11.9. With the Hubble constant at 67.8 km/s/Mpc ( according to the most recent survey with the Planck Satellite ) this means that the galaxies are at a distance of 14.24 billion light years ! With...
  37. N

    Exploring the Relationship Between Hubble Constant and $\phi$

    1. Homework Statement If \phi is a usual field is it possible that H\dot{\phi}=-\partial^2\phi/{\partial x^2} Where H is the Hubble constant and the dot denotes time derivative 2. Homework Equations H\dot{\phi}=-\partial^2\phi/{\partial x^2} 3. The Attempt at a Solution I tried different...
  38. C

    Using Hubble parameter defn to change integration variable from t to a

    Homework Statement r1 = t∫t1 1/a(t) dt Use the Hubble parameter definition to change from t to a, if a(t) = a and a(t1) = 1 Homework Equations Hubble parameter H = a' / a where a' = da/dt The Attempt at a Solution Start with Hubble parameter definition, and rearrange to find dt aH =...
  39. H

    Vacuum metastability referenced in Simplified chain inflation and Hubble time

    Vacuum metastability referenced in "Simplified chain inflation" and Hubble time In this paper http://power.itp.ac.cn/~huangqg/Publications/JCAP-Simplified%20chain%20inflation.pdf it is referenced(Ctrl+F 'with the lifetime of the metastable vacua much shorter than the Hubble time') that basically...
  40. Fightfish

    Hubble Space Telescope Diffraction Limit

    In the Hubble Space Telescope, light rays from a distant celestial object (1) first passes through an aperture window of diameter 3m (2) incident upon, and reflected by a primary mirror of diameter 2.4m (3) reflected by a secondary mirror of diameter 0.3m to form the final image. For the...
  41. J

    Why is the age of the Universe the reciprocal of the Hubble constant?

    According to the wikipedia entry, the latest values for the Lambda-CDM model parameters for the age of the Universe, t_0, and the Hubble constant, H_0 are t_0 = 13.75 \pm 0.11 \times 10^9 \mbox{ years} H_0 = 70.4 \pm 1.3 \mbox{ km s}^{-1} \mbox{Mpc}^{-1} If you combine the errors this implies...
  42. andrewkirk

    Why is the Hubble sphere expanding?

    Hubble’s law, according to Wikipedia, says that the recession velocity of a distant object P comoving with Earth is vrec=HD where H is Hubble’s constant and D is the proper distance from Earth to P. The Hubble sphere is the area of space in which all objects comoving with Earth have vrec less...
  43. P

    Need specific Hubble images. Archive does not have them.

    I'm doing a summer internship and my supervisor is currently away and uncontactable. He left me details of certain Hubble images to download and analyse asking for HST images of M31 with coordinates 00:42:52.534 +41:18:54.17 on 2006-07-15 and 2007-01-12. (YYYY-MM-DD) The problem is that...
  44. Y

    Carried along by the Hubble flow.

    Hi. If we fire a rocket into space at some significant fraction of the speed of light (say 0.1c) and then switch off the engines and let it cruise indefinitely, will it appear to accelerate away from us and in effect be carried along by the Hubble flow. Given a million or a billion years would...
  45. R

    What the Hubble constant must be set to if Univ is flat

    What must the Hubble constant be if the Universe is flat. At the Lamda CDM article on wiki it says 70.4 km/s mpc. I'm not sure if that's what it must be if the universe is flat or if that's what experiments have measured it to be, I'm 99% sure that it's the former but I want to be 100% sure...
  46. J

    Hubble Law - recession velcoity?

    Hubble Law - recession velcoity? v = H0d tells us that the recession velcotiy of a galaxy is directly related to its distance from us on earth However, as the planets move further apart, their potential energy increases (and hence kinetic energy decreases). How do these two phenomena tie...
  47. F

    Dark energy expansion and the Hubble diagram

    I understand that a Hubble diagram is a graph of recession velocity plotted against distance for distant galaxies, and shows a linear relationship. The Hubble constant is the gradient of the graph. We are now observing extremely distant galaxies with greater than expected velocities due to...
  48. F

    Distances to galaxies using the Hubble Relation: look-back time

    Hi all, this is my first post; apologies if it seems a bit basic, I suspect there's something fundamental I'm not getting here :smile: Say I observe the spectrum of a galaxy, and I calculate its redshift. I then use the Hubble Relation to find its distance, which is, say, ten billion light...
  49. C

    Why does comoving Hubble radius increase with time?

    I am looking at inflation at the moment, and it says in my textbook that (aH)^(-1) is constantly increasing in matter or radiation dominated epochs. a is always positive and always increasing. This tells me that da/dt is positive. I think that setting the universe to MD/RD means that da/dt...
  50. T

    Stargazing Is the Hubble Telescope Obsolete?

    Some years ago I read that the Hubble Telescope is obsolete because modern telescopes have adaptive and corrective optics that make a space telescope unnecessary(at least for visible light). Since new Earth based telescopes have the advantage of very large mirrors(10 meters for the Keck) vs 2.4...
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