Standout Hubble Images: 16 Pictures and What Makes Each Work

Thousands of Hubble images have been released since 1990. Picking sixteen means choosing a lens, and the one used here is visual: color, composition, form, tonal range and texture, the same qualities that make any photograph hold attention. A second filter is technical. Pictures from the Advanced Camera for Surveys and Wide Field Camera 3 are sharper and cleaner than those from earlier instruments, so they dominate. The third filter is meaning. Knowing what an image shows often transforms it, the way an inscription becomes readable once its alphabet is known.

Galaxies

1. NGC 1300 (ACS, 2005). The prototype of the barred spirals, a galaxy whose arms grow from the ends of a straight central bar. Hubble resolves dust lanes all the way into the nucleus, picks out star-forming knots in hydrogen light and shows background galaxies through the disk, which gives the picture real depth.

2. Arp 273 (WFC3, 2011). Released for Hubble's 21st anniversary, the pair at the top of this page shows a large spiral pulled into a rose-like shape by its smaller neighbor, which is thought to have passed right through it. Collisions produce the most varied shapes in the galaxy catalogs, and this is one of the most graceful.

3. Sombrero Galaxy, M104 (ACS, 2003). A spiral seen almost edge on: a dark band of dust across a glowing bulge, with globular clusters scattered around it like a swarm. A popular target for telescopes of every size, it gains a new layer in Hubble's detail, where each of those clusters shows as a small fuzzy star.

4. NGC 253 and 2MASX J00482185-2507365 (ACS, 2008). A study in layers. A small spiral sits in front of a larger one, betrayed by its dust darkening the light behind. Stars of the big galaxy NGC 253 dot the frame, and much more distant galaxies sit beyond both.

Nebulae

5. Carina Nebula mosaic (ACS and CTIO, 2007). One of the largest Hubble images ever assembled, stitched from 48 frames in the light of ionized hydrogen. Color came from lower-resolution ground-based images made at the Cerro Tololo Inter-American Observatory in Chile. Merging two data sets with very different sharpness gave the result a slightly painterly finish.

A wide panorama of the Carina Nebula: glowing red and gold clouds, dark dust and bright clusters of stars — The Carina Nebula mosaic, Hubble hydrogen-light frames with color from the Cerro Tololo Inter-American Observatory, released April 2007.Image: NASA, ESA, N. Smith (University of California, Berkeley), and The Hubble Heritage Team (STScI/AURA)

6. Mystic Mountain in the Carina Nebula (WFC3, 2010). A pillar of gas and dust with jets streaming from young stars at its peaks. The region was first spotted in the larger mosaic and then reimaged in full color, giving a landscape never seen in such detail.

7. Tarantula Nebula (WFC3, 2009). One of the largest star-forming regions known, in the Large Magellanic Cloud. Made soon after the last servicing mission, it shows a cluster of hot young stars blowing open a cavity in the cloud that formed them, in detail comparable to nebulae inside the Milky Way.

8. NGC 5189 (WFC3, 2012). A planetary nebula with an unusual point-symmetric, spiral form and colors to match. Planetary nebulae are far more varied in shape than anyone knew before Hubble, and this one shows why.

The planetary nebula NGC 5189, a twisted ribbon of glowing gas in blue, orange and gold — NGC 5189 in the constellation Musca, released in December 2012.Image: NASA, ESA and the Hubble Heritage Team (STScI/AURA)

9. Horsehead Nebula in infrared (WFC3/IR, 2013). Making a fresh picture of a famous subject is hard. In infrared light the dark silhouette known from countless photographs becomes a translucent, folded structure, because the dust that blocks visible light lets infrared through.

The Horsehead Nebula in infrared, a pale, translucent horse-head shape of gas and dust against a field of stars — The Horsehead Nebula, Barnard 33, in near-infrared light, released for Hubble's 23rd anniversary in April 2013.Image: NASA, ESA, and the Hubble Heritage Team (AURA/STScI)

10. Veil Nebula (WFC3, 2015). Part of the Cygnus Loop, the debris of a supernova. Hubble can only cover small patches of this huge structure, but each patch shows a tangle of fine, multicolored filaments.

Explosions and echoes

11. V838 Monocerotis light echo (ACS, 2003). As much an event as an object. Light from a stellar outburst travelled outward through older shells of dust, lighting them in turn, and the series of snapshots lets astronomers trace the shells in three dimensions.

12. SNR 0509-67.5 (ACS, 2010). A nearly perfect ring in the Large Magellanic Cloud, the expanding shell of a star that exploded about 400 years ago. It is really the thin surface of a sphere, and it is gently distorted by the thin gas between stars.

Planets and the deep universe

13. Saturn and its moons (WFPC2, 2009). Rings, banded clouds and moons with their shadows crossing the disk. Hubble's distance from Saturn allows the whole system to be seen and followed over years.

14. Hubble Deep Field (WFPC2, 1996). The most consequential of all. Nobody knew whether days of exposure on an empty-looking speck would show anything. It showed about 3,000 galaxies; covering the whole sky would take about 24 million such fields.

15. M31 halo (ACS, 2003). Stars in the Milky Way, stars in Andromeda and distant galaxies side by side, described in detail in The M31 Deep Field.

16. Abell 370 (ACS and WFC3/IR, 2017). A massive galaxy cluster whose gravity, mostly from dark matter, bends and magnifies the light of galaxies far behind it, an effect Einstein's theory predicts. The name comes from George Abell's catalog of more than 4,000 clusters, compiled from photographic plates taken with the 48-inch Schmidt telescope at Palomar Observatory.

Questions readers ask

What makes a Hubble image visually strong?

The same things as in any photograph: a clear composition, a full range of tones, color that separates features and texture worth looking into. Sharpness matters too, so newer cameras tend to produce stronger images. Knowing what the subject is adds another layer of interest.

Which Hubble cameras made these images?

Mostly the Advanced Camera for Surveys and Wide Field Camera 3, the two instruments with the best image quality. The Wide Field and Planetary Camera 2 contributed the Hubble Deep Field and the Saturn view, and the Carina mosaic adds ground-based color from Chile.

Why is the Hubble Deep Field so important?

Before it, no one knew how many faint, distant galaxies a long exposure on a blank patch of sky would find. The answer was about 3,000 in one tiny field, many farther away than any recorded before, which reshaped the study of how galaxies form and change.

What is the ring in SNR 0509-67.5?

It is the outer shell of debris from a supernova that exploded about 400 years ago in the Large Magellanic Cloud. The shell is a sphere, though in the picture it appears as a ring. Its outline is not perfectly round, because even the very thin gas between stars is enough to push it slightly out of shape as it expands.