Galaxy full of cosmic lighthouses

This enchanting spiral galaxy can be found in the constellation of Ursa Major (the Great Bear). Star-studded NGC 3972 lies about 65 million light-years away from the Earth, meaning that the light that we see now left it 65 million years ago, just when the dinosaurs became extinct.

NGC 3972 has had its fair share of dramatic events. In 2011 astronomers observed the explosion of a type Ia supernova in the galaxy (not visible in this image). These dazzling objects all peak at the same brightness, and are brilliant enough to be seen over large distances. NGC 3972 also contains many pulsating stars called Cepheid variables. These stars change their brightness at a rate matched closely to their intrinsic luminosity, making them ideal cosmic lighthouses for measuring accurate distances to relatively nearby galaxies.

Astronomers search for Cepheid variables in nearby galaxies which also contain a type Ia supernova so they can compare the true brightness of both types of stars. That brightness information is used to calibrate the luminosity of Type Ia supernovae in far-flung galaxies so that astronomers can calculate the galaxies' distances from Earth. Once astronomers know accurate distances to galaxies near and far, they can determine and refine the expansion rate of the Universe.

This image was taken in 2015 with Hubble’s Wide Field Camera 3, as part of a project to improve the precision of the Hubble constant — a figure that describes the expansion rate of the Universe.

Credit:

NASA, ESA, A. Riess (STScI/JHU)

About the Image

Id:potw1810a
Type:Observation
Release date:5 March 2018, 06:00
Size:4853 x 3640 px

About the Object

Name:NGC 3972
Type:Local Universe : Galaxy : Type : Spiral
Constellation:Ursa Major
Category:Galaxies

Image Formats

Large JPEG
4.5 MB
Screensize JPEG
197.6 KB

Zoomable


Wallpapers

1024x768
220.4 KB
1280x1024
363.0 KB
1600x1200
520.0 KB
1920x1200
655.3 KB
2048x1536
857.0 KB

Coordinates

Position (RA):11 55 45.20
Position (Dec):55° 19' 14.42"
Field of view:2.42 x 1.82 arcminutes
Orientation:North is 5.1° left of vertical

Colours & filters

BandWavelengthTelescope
Optical
V
555 nm Hubble Space Telescope
WFC3
Optical
I
814 nm Hubble Space Telescope
WFC3
Infrared
H
1.6 μm Hubble Space Telescope
WFC3
Optical
Long Pass
350 nm Hubble Space Telescope
WFC3

Also see our


Accelerated by CDN77