Exactly 85 years ago, on the 18th of February in 1930, a young researcher named Clyde Tombaugh was working at the Lowell Observatory in Flagstaff, Arizona. He had been tasked with looking for a trans-Neptunian planet, called planet X and it was on that night that he found it. On May 1 of that same year it was officially given the name Pluto.

Today, on the anniversary of that discovery, researchers with NASA’s New Horizons mission to Pluto were thrilled when the spacecraft returned its first images of Pluto’s smaller moons.

“Professor Tombaugh’s discovery of Pluto was far ahead its time, heralding the discovery of the Kuiper Belt and a new class of planet. The New Horizons team salutes his historic accomplishment,” said Alan Stern, New Horizons principal investigator from Southwest Research Institute, Boulder, Colorado in a statement.

Although the spacecraft won’t be up close to the distant dwarf-planet until July, the moons Nix and Hydra were visible in a series of images taken between January 27 and February 8.

The spacecraft was still 125 million to 115 million miles (201 million to 186 million kilometers) from Pluto so at this point the images are still only visible as a yellow diamond (Hydra) and an orange diamond (Nix). However, it is the best view researchers have ever had of Hydra and their only look to date at Nix.

The images, assembled into a seven frame movie, as well as other images returned by New Horizons are available for viewing on NASA’s New Horizons mission page.

“It’s thrilling to watch the details of the Pluto system emerge as we close the distance to the spacecraft’s July 14 encounter. This first good view of Nix and Hydra marks another major milestone, and a perfect way to celebrate the anniversary of Pluto’s discovery,” said John Spencer, New Horizons science team member also from Southwest Research Institute.

According to NASA researchers, these are the first in a series of long exposure images that will continue to be delivered until March with a goal of better understanding the orbits of Pluto’s moons.

Each frame represents the combination of five, 10 second images taken with the Long-Range Reconnaissance Imager (LORRI) on the New Horizons spacecraft.

Pluto has a total of five known moons; Charon, Nix, Hydra, Kerberos and Styx and there is a possibility that more will be discovered as New Horizons gets closer.

Charon, the first to be discovered, is almost half the size of Pluto itself. It was found by James Christy in 1978 when he observed that images of Pluto were strangely elongated.

Nix and Hydra were found by a team studying the Pluto system with the Hubble Space Telescope in 2005. Nix and Hydra are roughly 20 to 70 miles wide.

Kerberos, named after the three-headed dog of Greek mythology, has an estimated diameter of 8 to 21 miles was discovered on 28 June 2011 by a large team led by Mark Showalter using the Hubble Space Telescope. Styx was discovered in a Hubble survey in 2012 that was searching for potential hazards near Pluto for the New Horizons mission.

According to NASA, New Horizons’ closest approach to Pluto will be at 7:49:59 a.m. EDT on July 14, 2015.