Skip to main content

Stars sparkle and shine in Hubble image of a distant globular cluster

Another week, another beautiful image of space captured by the Hubble Space Telescope. This week’s image shows the globular cluster NGC 6717, located over 20,000 light-years away in the constellation of Sagittarius.

A global cluster is a dense group of stars, often thousands or even millions of stars strong, which is bound together by gravity. The clusters form roughly spherical shapes and mostly consist of less massive stars, each one typically less than the mass of our sun. As you can see in the image below, the stars are packed closer together nearer the center of the cluster and are more spaced out around its edges.

A star-studded image from the NASA/ESA Hubble Space Telescope depicts NGC 6717, which lies more than 20,000 light-years from Earth in the constellation Sagittarius.
This star-studded image from the NASA/ESA Hubble Space Telescope depicts NGC 6717, which lies more than 20,000 light-years from Earth in the constellation Sagittarius. NGC 6717 is a globular cluster, a roughly spherical collection of stars tightly bound together by gravity. Globular clusters contain more stars in their centers than their outer fringes, as this image aptly demonstrates; the sparsely populated edges of NGC 6717 are in stark contrast to the sparkling collection of stars at its center. ESA/Hubble and NASA, A. Sarajedini

As well as the globular cluster, you can see a few very bright stars shining out near the center of the image. These stars aren’t actually a part of the cluster, but rather are located between it and Earth.

Studying globular clusters is important to astronomers because they are some of the oldest objects in the universe, so looking at them can reveal how early stars and galaxies formed. However, imaging this globular cluster was a challenge because of where it is located. The constellation of Sagittarius is located in the same portion of the sky as the center of the Milky Way, where many stars in our galaxy shine brightly. The center of our galaxy is also full of dust and gas which absorb light and obscure the view behind it.

To capture this image through the dust and gas, Hubble used two of its instruments in combination: The Wide Field Camera 3 and the Advanced Camera for Surveys.

Editors' Recommendations

Georgina Torbet
Georgina is the Digital Trends space writer, covering human space exploration, planetary science, and cosmology. She…
Hubble sees the changing seasons on Jupiter and Uranus
[Jupiter: left] - The forecast for Jupiter is for stormy weather at low northern latitudes. A prominent string of alternating storms is visible, forming a ‘vortex street’ as some planetary astronomers call it. [Uranus: right] - Uranus’s north pole shows a thickened photochemical haze that looks similar to the smog over cities. Several little storms can be seen near the edge of the polar haze boundary. Note: The planets do not appear in this image to scale.

Our planet isn't the only place in the solar system with dramatic weather changes. Other planets in the solar system also experience seasons, depending on their distance from the sun, and that affects their climates. One of the many jobs of the Hubble Space Telescope is to monitor the changing seasons on other planets, particularly the larger outer planets which aren't so often observed. And this week, scientist have released their newest views of Jupiter and Uranus, taken by Hubble and showing seasonal changes on the two planets.

Jupiter is far from the sun, so most of its heat comes not from outside but from within. Jupiter is thought to have a very high core temperature, which may be a result of how it was formed but could also be topped up by processes inside the planet. As this heat escapes from the planet's interior, it affects its atmosphere which contains multiple layers and has unusual features like geometric storms at its poles.

Read more
A sparkling field of stars cluster together in Hubble image
This image shows just a portion of M55, the cluster as a whole appears spherical because the stars’ intense gravitational attraction pulls them together. Hubble’s clear view above Earth’s atmosphere resolves individual stars in this cluster. Ground-based telescopes can also resolve individual stars in M55, but fewer stars are visible.

A sea of stars sparkles in this image from the Hubble Space Telescope. Showing an tremendous cluster of stars called a globular cluster, this view is located in the galaxy Messier 55.

A globular cluster is a group of stars which is tens of thousands or even millions of stars, and which is held together by gravity. That's why these clusters tend to form spherical shapes as the forces of gravity hold the cluster together.

Read more
A small, fuzzy dwarf galaxy in our neighborhood captured by Hubble
UGCA 307 hangs against an irregular backdrop of distant galaxies in this image from the NASA/ESA Hubble Space Telescope. The small galaxy consists of a diffuse band of stars containing red bubbles of gas that mark regions of recent star formation, and lies roughly 26 million light-years from Earth in the constellation Corvus. Appearing as just a small patch of stars, UGCA 307 is a diminutive dwarf galaxy without a defined structure — resembling nothing more than a hazy patch of passing cloud.

This week's image from the Hubble Space Telescope shows a galaxy in our backyard, cosmically speaking, taken as part of a project to image nearby galaxies. Galaxy UGCA 307 is located 26 million light-years away in the constellation of Corvus, or The Crow, a small constellation visible from the southern hemisphere which was documented as far back as 1,000 years BCE.

There is just a small cluster of stars within this galaxy, as it is a type called a dwarf galaxy. These are defined as galaxies with just a few billion stars, which sounds like a lot until you compare it to the hundreds of billions of stars that are found in our galaxy, the Milky Way.

Read more