Tag Archives: Spitzer Space Telescope

The Event Horizon Telescope Team has Produced the First Image Showing the Shadow of a Black Hole

Updated 7 April 2020

Peter Lobner

The first image of a black hole was released on 10 April 2019  at a press conference in Washington D.C. held by the Event Horizon Telescope (EHT) team and the National Science Foundation (NSF).  The subject of the image is the supermassive black hole located near the center of the Messier 87 (M87) galaxy.  This black hole is about 55 million light years from Earth and is estimated to have a mass 6.5 billion times greater than our Sun.  The image shows a glowing circular emission ring surrounding the dark region (shadow) containing the black hole.  The brightest part of the image also may have captured a bright relativistic jet of plasma that appears to be streaming away from the black hole at nearly the speed of light, beaming generally in the direction of Earth.

The first ever image showing the shadow of a black hole (M87), which remains unseen at the center of the dark circular region.
Source:The EHT Collaboration, et al.

The EHT is not one physical telescope.  Rather, it an array of millimeter and sub-millimeter wavelength radio telescopes located around the world.  The following map shows the eight telescopes that participated in the 2017 observations of M87.  Three additional telescopes joined the EHT array in 2018 and later.  

The EHT array as used for the April 2017 observations.  
Source: The EHT Collaboration, et al.

All of the EHT telescopes are used on a non-dedicated basis by an EHT team of more than 200 researchers during a limited annual observing cycle.  The image of the M87 black hole was created from observations made during a one week period in April 2017.

The long baselines between the individual radio telescopes give the “synthetic” EHT the resolving power of a physical radio telescope with a diameter that is approximately equal to the diameter of the Earth. A technique called very long-baseline interferometry (VLBI) is used to combine the data from the individual telescopes to synthesize the image of a black hole. EHT Director, Shep Doeleman, referred to VLBI as “the ultimate in delayed gratification among astronomers.” The magnifying power of the EHT becomes real only when the data from all of the telescopes are brought together and the data are properly combined and processed. This takes time.

At a nominal operating wavelength of about 1.3 mm (frequency of 230 GHz), EHT angular resolution is about 25 microarcseconds (μas), which is sufficient to resolve nearby supermassive black hole candidates on scales that correspond to their event horizons.  The EHT team reports that the M87 bright emission disk subtends an angle of 42 ± 3 microarcseconds.

For comparison, the resolution of a human eye in visible light is about 60 arcseconds (1/60thof a degree; there are 3,600 arcseconds in one degree) and the 2.4-meter diameter Hubble Space Telescope has a resolution of about 0.05 arcseconds (50,000 microarcseconds).

You can read five open access papers on the first M87 Event Horizon Telescope results written by the EHT team and published on 10 April 2019 in the Astrophysical Journal Letters here:

Congratulations to the EHT Collaboration for their extraordinary success in creating the first-ever image of a black hole shadow.

7 April 2020 Update:  EHT observations were complemented by multi-spectral (multi-messenger) observations by NASA spacecraft

On 10 April 2019, NASA reported on its use of several orbiting spacecraft to observe M87 in different wavelengths during the period of the EHT observation.

  • “To complement the EHT findings, several NASA spacecraft were part of a large effort, coordinated by the EHT’s Multiwavelength Working Group, to observe the black hole using different wavelengths of light. As part of this effort, NASA’s Chandra X-ray Observatory, Nuclear Spectroscopic Telescope Array (NuSTAR) and Neil Gehrels Swift Observatory space telescope missions, all attuned to different varieties of X-ray light, turned their gaze to the M87 black hole around the same time as the EHT in April 2017. NASA’s Fermi Gamma-ray Space Telescope was also watching for changes in gamma-ray light from M87 during the EHT observations.”
  • “NASA space telescopes have previously studied a jet extending more than 1,000 light-years away from the center of M87. The jet is made of particles traveling near the speed of light, shooting out at high energies from close to the event horizon. The EHT was designed in part to study the origin of this jet and others like it.”

NASA’s Neutron star Interior Composition Explorer (NICER) experiment on the International Space Station also contributed to the multi-spectral observations of M87, which were coordinated by EHT’s Multiwavelength Working Group.

Chandra X-ray Observatory close-up of the core of the M87 galaxy,
showing the location of the black hole (+) and the relativistic jet.
Source: NASA/CXC/Villanova University/J. Neilsen

On April 25, 2019, NASA released the following composite image showing the M87 galaxy, the position of the black hole and large relativistic jets of matter being ejected from the black hole.  These infrared images were made by NASA’s orbiting Spitzer Space Telescope.  

The M87 galaxy, with two expanded views, first showing the location of the black hole and two plasma jets (orange) at the center of M87, and second, the closeup EHT image of the black hole’s shadow.  
Source: NASA/JPL-Caltech/IPAC/Event Horizon Telescope

For more information:

See the following sources for more information on the EHT and imaging the M87 black hole:

Remarkable Multispectral View of Our Milky Way Galaxy

Peter Lobner

Moody Blues cover - In search of the lost chordAlbum cover art credit: Deram Records

Some of you may recall the following lyrics from the 1968 Moody Blues song, “The Word,” by Graeme, Edge, from the album “In Search of the Lost Chord”:

This garden universe vibrates complete

Some, we get a sound so sweet

 Vibrations reach on up to become light

And then through gamma, out of sight

Between the eyes and ears there lie

The sounds of color and the light of a sigh

And to hear the sun, what a thing to believe

But it’s all around if we could but perceive

 To know ultraviolet, infrared and X-rays

Beauty to find in so many ways

On 24 February 2016, the European Southern Observatory (ESO) Consortium announced that it has completed the ATLASGAL Survey of the Milky Way. The survey mapped the entire galactic plane visible from the southern hemisphere at sub-millimeter wavelengths, between infrared light and radio waves, using the Atacama Pathfinder EXperiment (APEX) telescope located at 5,100 meters (16,732 ft.) above sea level in Chile’s Atacama region. The southern sky is particularly important because it includes the galactic center of our Milky Way. The Milky Way in the northern sky has already been mapped by the James Clerk Maxwell Telescope, which is a sub-millimeter wavelength telescope at the Mauna Kea Observatory in Hawaii.

The new ATLASGAL maps cover an area of sky 140 degrees long and 3 degrees wide. ESO stated that these are the sharpest maps yet made, and they complement those from other land-based and space-based observatories. The principal space-based observatories are the following:

  • European Space Agency’s (ESA) Plank satellite: Mission on-going, mapping anisotropies of the cosmic microwave background at microwave and infrared frequencies.
  • ESA’s Herschel Space Observatory: Mission on-going, conducting sky surveys in the far-infrared and sub-millimeter frequencies.
  • National Aeronautics and Space Administration (NASA) Spitzer Space Telescope: Mission on-going, conducting infrared observations and mapping as described in my 1 April 2015 post.
  • NASA’s Hubble Space Telescope: Mission on-going, observing and mapping at ultraviolet, optical, and infrared frequencies.
  • NASA’s Chandra X-Ray Observatory: Mission on-going, observing and mapping X-ray sources.
  • NASA’s Compton Gamma Ray Observatory: Mission ended in 2000. Observed and mapped gamma ray and x-ray sources.

ESO reported that the combination of Planck and APEX data allowed astronomers to detect emission spread over a larger area of sky and to estimate from it the fraction of dense gas in the inner galaxy. The ATLASGAL data were also used to create a complete census of cold and massive clouds where new generations of stars are forming.

You can read the ESO press release at the following link:


Below is a composite ESO photograph that shows the same central region of the Milky Way observed at different wavelengths.

ESO Multispectral view of Milky WayCredit: ESO/ATLASGAL consortium/NASA/GLIMPSE consortium/VVV Survey/ESA/Planck/D. Minniti/S. Guisard. Acknowledgement: Ignacio Toledo, Martin Kornmesser

  • The top panel shows compact sources of sub-millimeter radiation detected by APEX as part of the ATLASGAL survey, combined with complementary data from ESA’s Planck satellite, to capture more extended features.
  • The second panel shows the same region as seen in shorter, infrared, wavelengths by the NASA Spitzer Space Telescope
  • The third panel shows the same part of sky again at even shorter wavelengths, the near-infrared, as seen by ESO’s VISTA infrared survey telescope at the Paranal Observatory in Chile. Regions appearing as dark dust tendrils in the third panel show up brightly in the ATLASGAL view (top panel).
  • The bottom panel shows the more familiar view in visible light, where most of the more distant structures are hidden from view

NASA’s Goddard Space Flight Center also has created a multispectral view of the Milky Way, which you will find at the following link:


Following is a composite NASA photograph that shows the same central regions of the Milky Way observed at different wavelengths.

NASA Goddard multispectralSource: NASA Goddard Space Flight Center

Starting from the top, the ten panels in the NASA image cover the following wavelengths.

  • Radio frequency (408 MHz)
  • Atomic hydrogen
  • Radio frequency (2.5 GHz)
  • Molecular hydrogen
  • Infrared
  • Mid-infrared
  • Near-infrared
  • Optical
  • X-ray
  • Gamma ray

The Moody Blues song, “The Word,” ends with the following lyrics:

 Two notes of the chord, that’s our full scope

But to reach the chord is our life’s hope

And to name the chord is important to some

So they give it a word, and the word is “Om”

While “Om” (pronounced or hummed “ahh-ummmm”) traditionally is a sacred mantra of Hindu, Jain and Buddhist religions, it also may be the mantra of astronomers as they unravel new secrets of the Milky Way and, more broadly, the Universe. I suspect that completing the ATLASGAL Survey of the Milky Way was an “Om” moment for the many participants in the ESO Consortium effort.

Spitzer Space Telescope “Warm Mission” Continued into 2020

Peter Lobner

Updated 19 February 2020

The Spitzer Space Telescope, an infrared space observatory, was launched on 8 August 2003 into an “earth-trailing” orbit around the Sun. It is one of four “Great Observatories” launched by NASA; the others being the Hubble Space Telescope, the Compton Gamma-ray Observatory; and the Chandra X-ray Observatory.

Spitzer_Telescope_Handbook013   Diagram source: NASA

The primary mirror is 85 cm in diameter, made of beryllium, and until May 2009, was cooled by liquid helium to 5.5 degrees K. With the on-board liquid helium supply exhausted, most of the instruments were no longer usable. However, the two shortest wavelength modules of the Infrared Science Archive (IRAC) camera remained operable at their original sensitivities. This allowed the mission team to continue with the “Spitzer Warm Mission”.

You can read about the design of the Spitzer Space Telescope at the following link:


An example of an image from the Spitzer Space Telescope is this view of Eta Carinae:

The tortured clouds of Eta Carinae  Photo source: NASA

You can see this and many other images from the Spitzer telescope, and related image data, at the following NASA / JPL / Caltech website:


Update 19 February 2020

On 30 January 2020, NASA reported,

“After more than 16 years studying the universe in infrared light, revealing new wonders in our solar system, our galaxy and beyond, NASA’s Spitzer Space Telescope’s mission has come to an end…..the spacecraft was placed in a safe mode, ceasing all scientific operations.”

You can read the NASA announcement and a summary of the accomplishments of the Spitzer mission here: