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Hubble Images a Classic Spiral

A spiral galaxy with three prominent arms wrapping around it. The galaxy holds plenty of extra gas and dark dust between the arms. There are shining blue points throughout the arms and some patches of gas out beyond the galaxy’s edge, where stars are forming. The center of the galaxy also shines brightly. It is on a dark background where some small orange dots mark distant galaxies.

This NASA/ESA Hubble Space Telescope image features the majestic spiral galaxy NGC 3430.

ESA/Hubble & NASA, C. Kilpatrick

This NASA/ESA Hubble Space Telescope image treats viewers to a wonderfully detailed snapshot of the spiral galaxy NGC 3430 that lies 100 million light-years from Earth in the constellation Leo Minor. Several other galaxies, located relatively nearby to this one, are just beyond the frame of this image; one is close enough that gravitational interaction is driving some star formation in NGC 3430 — visible as bright-blue patches near to but outside of the galaxy’s main spiral structure. This fine example of a galactic spiral holds a bright core from which a pinwheel array of arms appears to radiate outward. Dark dust lanes and bright star-forming regions help define these spiral arms.

NGC 3430’s distinct shape may be one reason why astronomer Edwin Hubble used to it to help define his classification of galaxies. Namesake of the Hubble Space Telescope, Edwin Hubble authored a paper in 1926 that outlined the classification of some four hundred galaxies by their appearance — as either spiral, barred spiral, lenticular, elliptical, or irregular. This straightforward typology proved extremely influential, and the detailed schemes astronomers use today are still based on Edwin Hubble’s work. NGC 3430 itself is a spiral lacking a central bar with open, clearly defined arms — classified today as an SAc galaxy.

Astronomer Edwin Hubble pioneered the study of galaxies based simply on their appearance. This "Field Guide" outlines Hubble's classification scheme using images from his namesake telescope. Credit: NASA's Goddard Space Flight Center; Lead Producer: Miranda Chabot; Lead Writer: Andrea Gianopoulos