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Cloud 9, Starless Gas Cloud Compass Image
This is an annotated composite image of Cloud-9, a Reionization-Limited H I Cloud (RELHIC), as captured by the Hubble Space Telescope’s ACS (Advanced Camera for Surveys) and the ground-based Very Large Array (VLA) radio telescope.
The image shows a scale bar, compass arrows, and color key for reference.
The scale bar is labeled in light-years along the top, which is the distance that light travels in one Earth-year. (It takes 2,000 years for light to travel a distance equal to the length of the scale bar.) One light-year is equal to about 5.88 trillion miles or 9.46 trillion kilometers.
The scale bar is also labeled in arcseconds, which is a measure of angular distance on the sky. One arcsecond is equal an angular measurement of 1/3600 of one degree. There are 60 arcseconds in an arcminute and 60 arcminutes in a degree. (The full Moon has an angular diameter of about 30 arcminutes.) The actual size of an object that covers one arcsecond on the sky depends on its distance from the telescope.
The north and east compass arrows show the orientation of the image on the sky. Note that the relationship between north and east on the sky (as seen from below) is flipped relative to direction arrows on a map of the ground (as seen from above).
This image shows wavelengths of light, including radio waves, that have been translated into visible-light colors. The color key shows the two ACS filters used to collect the light, along with the VLA’s radio-wave contribution. A color key shows F606W in blue, F814W in orange, and Radio VLA in magenta.
About the Object
- R.A. PositionR.A. PositionRight ascension – analogous to longitude – is one component of an object's position.12:51:51.33
- Dec. PositionDec. PositionDeclination – analogous to latitude – is one component of an object's position.+40:18:05.46
- ConstellationConstellationOne of 88 recognized regions of the celestial sphere in which the object appears.Ursa Major
- DistanceDistanceThe physical distance from Earth to the astronomical object. Distances within our solar system are usually measured in Astronomical Units (AU). Distances between stars are usually measured in light-years. Interstellar distances can also be measured in parsecs.About 14 million light-years
- DimensionsDimensionsThe physical size of the object or the apparent angle it subtends on the sky.Image is 2.4 arcmin across (about 10,000 light-years)
About the Data
- Data DescriptionData DescriptionProposal: A description of the observations, their scientific justification, and the links to the data available in the science archive.
Science Team: The astronomers who planned the observations and analyzed the data. "PI" refers to the Principal Investigator.The Hubble observations include those from program 17712 (A. Benitez-Llambay)
- InstrumentInstrumentThe science instrument used to produce the data.ACS/WFC
- Exposure DatesExposure DatesThe date(s) that the telescope made its observations and the total exposure time.February 17-19, 2025
- FiltersFiltersThe camera filters that were used in the science observations.F606W, F814W
- Object NameObject NameA name or catalog number that astronomers use to identify an astronomical object.Cloud 9
- Object DescriptionObject DescriptionThe type of astronomical object.Starless gas cloud
- Release DateJanuary 5, 2026
- Science ReleaseNASA’s Hubble Examines Cloud-9, First of New Type of Object
- CreditScience: NASA, ESA, VLA, Gagandeep Anand (STScI), Alejandro Benitez-Llambay (University of Milano-Bicocca); Image Processing: Joseph DePasquale (STScI)
These images were acquired by the ACS Instrument on the Hubble Space Telescope. The color results from assigning different hues (colors) to a monochromatic (grayscale) image. In this case, the assigned colors are: Cyan: F606W, Orange: F814W
Related Images & Videos
Cloud 9, Starless Gas Cloud
Magenta is radio data from the ground-based Very Large Array (VLA) showing the presence of Cloud-9. The dashed circle marks the area where researchers focused their search for stars. Hubble found no stars within Cloud-9. The few objects within its boundaries are background galaxies.
Cloud 9, Starless Gas Cloud Video
This annotated video shows the location of Cloud-9 on the sky. As the video zooms into this gas-rich, dark-matter cloud, it becomes evident that there are no stars within it. Only background galaxies appear behind Cloud-9, which has survived since the universe’s early days....
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Claire Andreoli
NASA’s Goddard Space Flight Center
Greenbelt, Maryland
claire.andreoli@nasa.gov
