Eye of the Galaxy

This finely detailed image shows the heart of NGC 1097, a barred spiral galaxy that lies about 48 million light-years from Earth in the constellation Fornax. This picture reveals the intricacy of the web of stars and dust at NGC 1097’s centre, with the long tendrils of dust picked out in a dark red hue. The extent to which the galaxy’s structure is revealed is thanks to two instruments on the NASA/ESA Hubble Space Telescope: the Wide Field Camera 3  (WFC3) and the Advanced Camera for Surveys  (ACS).

The idea that a single image can be taken using two different cameras is not very intuitive. However, it makes far more sense after delving into how beautiful astronomical images like this one are composed. A helpful starting point is to consider what colour is, exactly. Our eyes can detect light waves at optical wavelengths between roughly 380 and 750 nanometres, using three types of receptors, each of which is sensitive to just a slice of that range. Our brain interprets these specific wavelengths as colours. By contrast, a telescope camera like the WFC3 or ACS is sensitive to a single, broad range of wavelengths to maximise the amount of light collected. Raw images from telescopes are always in greyscale, only showing the amount of the light captured across all those wavelengths.

Colour images from telescopes are indirectly possible, however, with the help of filters. By sliding a filter over the aperture of an instrument like the WFC3 or ACS, only light from a very specific wavelength range is let through — one such filter used in this image is for green light around 555 nanometres. This yields a greyscale image showing only the amount of light with that wavelength. This multicolour image of NGC 1097 is composed of images using seven different filters in total. 

Credit:

ESA/Hubble & NASA, D. Sand, K. Sheth

About the Image

Id:potw2211a
Type:Observation
Release date:14 March 2022, 06:00
Size:7418 x 3943 px

About the Object

Name:NGC 1097
Type:Unspecified : Galaxy : Type : Spiral
Constellation:Fornax
Category:Galaxies

Image Formats

Large JPEG
16.1 MB
Screensize JPEG
193.3 KB

Zoomable


Wallpapers

1024x768
333.9 KB
1280x1024
583.1 KB
1600x1200
889.7 KB
1920x1200
1.1 MB
2048x1536
1.5 MB

Coordinates

Position (RA):2 46 19.69
Position (Dec):-30° 16' 53.40"
Field of view:4.90 x 2.61 arcminutes
Orientation:North is 48.7° right of vertical


Colours & filters

BandWavelengthTelescope
Ultraviolet
UV
275 nm Hubble Space Telescope
WFC3
Optical
u
336 nm Hubble Space Telescope
WFC3
Optical
B
438 nm Hubble Space Telescope
WFC3
Optical
Strömgren y
547 nm Hubble Space Telescope
WFC3
Optical
V
555 nm Hubble Space Telescope
WFC3
Optical
I
814 nm Hubble Space Telescope
ACS
Optical
I
814 nm Hubble Space Telescope
WFC3
Optical
H-alpha + N II
657 nm Hubble Space Telescope
WFC3

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