New features of a galaxy that was discovered 170 years ago were caught in a new image of the M51a galaxy, also known as the "Whirlpool Galaxy."

The image is the result of 20 hours of exposure, according to a press release from Case Western Reserve University (CWRU). The photograph renders clear details of the northwest trail, which is 120,000 light-years long, and calls attention to the lack of stars in the southeast.

"These features can be used in future modeling to understand the history of M51, when it and its companion galaxy first started to interact," said lead study author Aaron Watkins, a PhD student in astronomy at CWRU.

"No professional astronomer we know of has ever taken such a deep image of this galaxy," Watkins said, according to the press release. Watkins believes the study of M51a would benefit from a look by the Hubble Space Telescope.

The findings were published in Astrophysical Journal Letters.

M51a was first identified in 1845 by Parsons, the Earl of Rosse. M51a has a smaller partner galaxy, M51b. Both lie in the Canes Venatici constellation, 31 million light-years away.