The Hubble Space Telescopeâ€˜s keen eye has revealed a previously undetected moon orbiting Neptune.Â The July 1, 2013 discoveryÂ , 24 years after Voyager 2 swung by the icy-blue giant, expands the known retinue of circling moons to 14.
Known only by its temporary designation â€”S/20044 N1â€”the tiny celestial piece of real estate measures no more than 12 miles (19 kilometers) across and appears to have escaped detection until now because of itsÂ extreme faintness and far flung orbit beyond the planetâ€™s ring fragment system known as arcs.
According toÂ Mark Showalter, a planetary astronomer at the SETI Institute in California who discovered the moon, the newfound object is almost 100 million times fainter than the faintest star visible to the naked eye. But by tracking the movements of a mysterious white dot visible on 150 Neptune photographs taken by Hubble between 2004 and 2009, he managed to pin down this mini-moon.
â€œThe moons and arcs orbit very quickly, so we had to devise a way to follow their motion in order to bring out the details of the system,â€ he said in a statement issued by NASA on Monday. â€œItâ€™s the same reason a sports photographer tracks a running athleteâ€”the athlete stays in focus, but the background blurs.â€
S/20044 N1 orbits between the Neptunian moons Larissa and Proteus, and circles the planet once every 23 hours at an altitude of 65,400 miles (104,000 kilometers).