More Information

Credits

Celestial-Terrestrial Convergence was developed and funded by the Hubble Mission at the Space Telescope Science Institute, and Zoltan Levay.

Photography and exhibit design: Zolt Levay
Science consulting: Brandon Lawton
Writing: Margaret W. Carruthers
Graphics: Elizabeth Wheatley
Website design: Pam Jeffries
Additional contributions: Greg Bacon, Claire Blome, John Godfrey, Hussein Jirdeh, John Maple, Denise Smith, Sharon Toolan, Vonessa Schulze

Special thanks to the Art Association of Jackson Hole and Executive Director Mark Nowlin for hosting the exhibit.

 

a. Telescope Name: All of the images shown are photographs of light collected by NASA’s Hubble Space Telescope. In one case (Carina Nebula), the image is constructed using a combination of Hubble data and photographs from a ground-based observatory, the Cerro Tololo Inter-American Observatory in Chile.

b. Object Name: While some objects have common names related to their appearance or location, others are referred to only by their catalog numbers.


Arp: Galaxies with unusual shapes included in Halton Arp’s Atlas of Peculiar Galaxies, published in 1966
HCG: Group of four or more galaxies included in Paul Hickson’s catalog of Compact Groups of Galaxies, first published in 1982
M: Messier objects, cataloged by or based on observations made by Charles Messier in the late 18th century
NGC: Objects included in the New General Catalogue of Nebulae and Clusters of Stars, first published by John Emil Louis Dreyer in the late 19th century; the catalog has been updated a number of times


c. Constellations: Astronomers divide the sky into 88 adjoining regions, each named for a prominent constellation. The constellation given for each celestial landscape in this exhibit reflects its location in the sky, as seen from Earth.


d. Year: Year that the image was released to the public.


e. Credits: Credits reflect the organizations and teams involved in transforming Hubble data into the images shown here.

AURA: Association of Universities for Research in Astronomy
ESA: European Space Agency
Hubble Heritage: A project founded in 1998 dedicated to finding and publicizing visually compelling photographs from the Hubble Space Telescope. The Hubble Heritage team is composed of astronomers, image processing specialists, and telescope experts based at the Space Telescope Science Institute
NASA: National Aeronautics and Space Administration
STScI: Space Telescope Science Institute
SM4  ERO: Servicing Mission 4, Early Release Observation: observations made in 2009 to demonstrate upgrades made to Hubble during the last servicing mission


f. Exposure Date: The date that the image data were collected. Most images are constructed with data collected over a series of Hubble orbits. Some reflect data collected over a number of years (not continuously).


g. Instrument: In addition to the mirrors designed to collect and focus light from space, Hubble also includes of a set of scientific instruments designed to analyze light in different ways. The instruments used for the images shown here include:


ACS: The Advanced Camera for Surveys was designed to survey large areas of the sky. ACS was installed with several channels, including the Wide Field Channel (WFC), High Resolution Channel (HRC), and Solar-Blind Channel (SBC). ACS was installed during Hubble’s fourth servicing mission, in 2002.
WFPC2: The Wide Field Planetary Camera 2 was installed on Hubble during the first servicing mission, in 1993, and remained Hubble’s main camera until installation of the ACS in 2002.
WFC3: The Wide Field Camera 3 is designed to look at a range of objects, detecting not just visible, but also ultraviolet and near infrared light. WFC3 has two channels: ultraviolet-visible (UVIS) and near-infrared (IR). WFC3 replaced the WFPC2 in 2009.


Find out more about Hubble instruments.

h. Exposure time: Total number of hours that Hubble spent collecting light from the object. More time is required for fainter objects.

i. Filters: When Hubble images an object in the sky, it does not capture all of the wavelengths (colors) of light at once. Instead, various filters are used: Each filter blocks out colors that the astronomers are not interested in, allowing only certain wavelengths or ranges of wavelengths into the detectors. The choice of filters depends on the type of object being observed (e.g., star vs. nebula) and what the astronomers are trying to find out about the object (e.g., its composition, structure, temperature, or motion) .

Filters are named by the specific wavelength or dominant wavelength of light that they let through: 502 nm = 502 nanometers (1,000,000,000 nm = 1 meter). Some of these wavelengths correspond to the wavelengths of light emitted by specific elements, like hydrogen, oxygen, or sulfur. Letters in parentheses refer to standard filters recognized across astronomy.

j. Color Assignments: The final images are made by assigning each filter a color, and then combining the colors. In most cases, the colors that are assigned to a specific filter are representative of the actual color of visible light that is being measured. For example, to create the Saturn image, the 439 nm filter was assigned as blue; the 555 nm as green, and the 675 nm as red. The image looks like Saturn looks to our eyes because we actually see light with wavelength of 439 nm as blue; 555 nm as yellowish-green, and 675 nm as orange-red.  In other cases, colors are chosen to better show the composition or structure of the object, and the colors don’t really show us the true color of the object. Finally, some of the images in this exhibit include ultraviolet or infrared, as well as visible light. Our eyes cannot detect UV or IR, but those filters are also assigned a visible color so that we can visualize the data. Because UV is just beyond the violet end of the visible-light spectrum (ultraviolet), it is often assigned a blue or purple color; IR is just beyond the red end, and is generally assigned a red color.

k. Description: Information about each image is based on careful scientific analysis of Hubble data by astronomers and astrophysicists across the world. Additional information about the research and the scientists involved in each project can be found on the Find out more links. Click here for definitions of terms used in the descriptions.

 Definitions for more astronomy terms can be found here.

Additional Information

Visit Hubblesite.org for more information about the Hubble Space Telescope; the objects, processes, and materials shown in the images; the data used to construct each image; the scientific investigations that each image is tied to; and NASA’s future missions, the James Webb Space Telescope and WFIRST.

For more information on how Hubble images are constructed and the convergence of art and science in Hubble images and American landscapes, see Hubble’s Legacy: Reflections by those who dreamed it, built it, and observed the universe with it (Roger D. Launius and David H. DeVorkin, Eds., 2014) 

  • “Creating Hubble’s Imagery” by Zolt Levay (Chapter 9)
  • “Displaying the Beauty of the Truth: Hubble Images as Art and Science” by Elizabeth Kessler (Chapter 10)
    Barred spiral
    Spiral galaxy in which the arms curl out from the ends of a central rod-shaped collection of stars, gas, and dust, rather than from a central point.
    Charged particles
    Tiny objects with a positive or negative electrical charge; free electrons or atoms with unequal numbers of protons and electrons.
    Coronagraph
    A tool that is used to block starlight. Coronagraphs simulate eclipses, allowing astronomers to image the space immediately surrounding the star.
    Dark energy
    A poorly understood force that appears to be counteracting the gravitational pull of galaxies, causing the universe to expand at an increasing rate over time.
    Dark matter
    A mysterious substance that is known to astronomers only by virtue of the fact that it exerts a gravitational pull. Dark matter does not emit, absorb, reflect, or block any form of light and thus is not visible in any way.
    Dust
    Solid, fine-grained material that blocks, scatters, and reflects visible starlight.
    Eclipse
    An event in which the line of sight between an observer and a bright object is blocked by another object. A solar eclipse occurs when the Moon comes between the Sun and Earth; a lunar eclipse occurs when Earth comes between the Sun and Moon.
    Electromagnetic radiation
    Any form of light, including radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays.
    Electromagnetic spectrum
    The range of light from very long-wavelength, low-energy radio waves to extremely short-wavelength, high-energy gamma rays; visible light is in the middle of the electromagnetic spectrum.
    Elliptical galaxy
    A roughly spherical or egg-shaped galaxy made of stars that are arranged in a cloud-like mass.
    Galaxy
    A group of millions to billions of stars, gas, dust, and dark matter held together by gravity.
    Galaxy cluster
    A group of several to thousands of galaxies held together by their mutual gravitational attraction.
    Gas
    Matter that is made of individual atoms and molecules that can move independently of each other.
    Gravitational lensing
    The magnification of light from deep space by a mass located between the light source and the observer; the effect is a result of the bending of light as it moves through space that is warped by the mass. The curved space behaves like a lens, redirecting light rays to us that may have otherwise missed our telescopes.
    Infrared
    A form of invisible electromagnetic radiation (light) that has wavelengths longer than visible light, but shorter than microwave radiation.
    Light-year
    The distance that light (any form of electromagnetic radiation) travels in one year. One light-year is equal to about six trillion miles.
    Light
    Any form of electromagnetic radiation; the term is often used exclusively to refer to visible light, but technically also includes light that cannot be detected by the human eye (e.g., infrared and ultraviolet). The Hubble Space Telescope detects ultraviolet, visible, and near-infrared light.
    Near-infrared (NIR)
    A form of invisible electromagnetic radiation (light) that is just beyond red in the spectrum. Some of Hubble’s instruments are designed to detect near-infrared.
    Nebula
    A cloud of gas and dust found between stars or surrounding stars. Some nebulae are in the process of forming stars, while others are the remnants of dead or dying stars that have shed much of their material into space.
    Spiral galaxy
    A galaxy in which stars are concentrated in arms that spiral out from the center of a relatively flat disk.
    Star
    A large glowing mass of charged particles (plasma) that is held together by gravity, and that glows as a result of nuclear fusion reactions taking place in its core.
    Starburst galaxy
    A galaxy in which stars are forming at a relatively high rate.
    Stellar wind
    A stream of charged particles that blows out from a star.
    Supernova
    An explosion of a massive star that has reached the end of its life.
    Supernova remnant
    Material that has been blown out from a massive star during a supernova, and material that is left over after a star has exploded./dd>
    Ultraviolet
    A form of invisible electromagnetic radiation (light) that has wavelengths shorter than visible light, but longer than X-rays. Some of Hubble’s instruments are designed to detect ultraviolet light.
    Visible light
    Light that humans can see; the range of the electromagnetic spectrum that the human eye can detect. Visible light includes the all of the colors of the rainbow, from long wavelength red (around 700 nanometers) to short wavelength violet (around 400 nm).
    Wavelength
    The distance between two peaks of a wave. Different types of light have different wavelengths. Different colors of visible light have different wavelengths.
    X-ray
    A type of high-energy electromagnetic radiation, with shorter wavelengths than ultraviolet light. X-rays are a type of light that human eyes cannot detect, but that some space telescopes can detect.