1 min read

Hubble View of a Cosmological Measuring Tape

A swirl of dust and light on a field of stars
This NASA/ESA Hubble Space Telescope image shows the spiral galaxy NGC 3021 which lies about 100 million light-years away in the constellation of Leo Minor (The Little Lion). Among many other types of stars, this galaxy contains Cepheid variable stars, which can be used work out the distance to the galaxy. These stars pulsate at a rate that is closely related to their intrinsic brightness, so measurements of their rate of pulsation and their observed brightness give astronomers enough information to calculate the distance to the galaxy itself.
NASA & ESA; Acknowledgement: A. Riess, STScI

This NASA/ESA Hubble Space Telescope image shows the spiral galaxy NGC 3021 which lies about 100 million light-years away in the constellation of Leo Minor (The Little Lion).

Among many other types of stars, this galaxy contains Cepheid variable stars, which can be used work out the distance to the galaxy. These stars pulsate at a rate that is closely related to their intrinsic brightness, so measurements of their rate of pulsation and their observed brightness give astronomers enough information to calculate the distance to the galaxy itself.

Cepheids are also used to calibrate an even brighter distance marker that can be used over greater distances: Type Ia supernovae. One of these bright exploding stars was observed in NGC 3021, back in 1995.

In addition, the supernova in NGC 3021 was also used to refine the measurement of what is known as the Hubble constant. The value of this constant defines how fast the Universe is expanding and the more accurately we know it the more we can understand about the evolution of the Universe in the past as well as in the future. So, there is much more to this galaxy than just a pretty spiral.

Text Credit: European Space Agency

Share

Details

Last Updated
Mar 05, 2024
Editor
NASA Hubble Mission Team
Contact
NASA Hubble Mission Team

Related Terms

Explore More

A close-up of a spiral galaxy, seen face-on. Its center is a bright white point, surrounded by a large yellowish oval with thin lines of dust swirling in it. From the sides of the oval emerge two bright spiral arms which wind through the round disk of the galaxy, filled with shining pink spots where stars are forming and more dark reddish dust. Many stars are visible in the foreground, over and around the galaxy.
2 min read

Hubble Images a Grand Spiral

Article2 days ago
4 min read

NASA Successfully Integrates Roman Mission’s Telescope, Instruments

NASA’s Nancy Grace Roman Space Telescope team has successfully integrated the mission’s telescope and two instruments onto the instrument carrier, marking the completion of the Roman payload. Now the team at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, will begin joining the payload to the spacecraft. “We’re in the middle of an exciting stage […]

Article2 days ago
Hundreds of overlapping objects at various distances are spread across this field. Galaxies’ colors vary. The majority appear orange, pink, and white, some are shades of orange or blue. Most galaxies appear as fuzzy ovals, but a few have distinctive spiral arms. At the very center is a tiny galaxy nicknamed Firefly Sparkle that looks like a long, angled, dotted line. Smaller companions are nearby.
6 min read

Found: First Actively Forming Galaxy as Lightweight as Young Milky Way

Article3 days ago
Keep Exploring

Discover More Topics From NASA

James Webb Space Telescope

The image is divided horizontally by an undulating line between a cloudscape forming a nebula along the bottom portion and a comparatively clear upper portion. Speckled across both portions is a starfield, showing innumerable stars of many sizes. The smallest of these are small, distant, and faint points of light. The largest of these appear larger, closer, brighter, and more fully resolved with 8-point diffraction spikes. The upper portion of the image is blueish, and has wispy translucent cloud-like streaks rising from the nebula below. The orangish cloudy formation in the bottom half varies in density and ranges from translucent to opaque. The stars vary in color, the majority of which have a blue or orange hue. The cloud-like structure of the nebula contains ridges, peaks, and valleys – an appearance very similar to a mountain range. Three long diffraction spikes from the top right edge of the image suggest the presence of a large star just out of view.

Perseverance Rover

Parker Solar Probe

Juno