Deep space images taken by advanced telescopes and arrays are starting to pay off in new ways. Such images, of course, paid immediate dividends by showing scientists and the rest of us parts of space that were very far away. They allowed us to discover new stars, new galaxies, new planets and closer looks at phenomenon like black holes and quasars.

However, now that these collections have been accumulating for a few decades new rewards are available. For example, astronomers are able to observe objects and processes over time.

In one such case, two images of a young star taken 18 years apart have provided astronomers with a look at how massive stars form in the earliest stages of formation.

The images came from the National Science Foundation’s Karl G. Jansky Very Large Array (VLA). Taken in 1996 and 2014, they show a massive young star called W75N(B)-VLA 2 forming about 4200 light years from Earth.

“The comparison is remarkable we’re seeing this dramatic change in real time, so this object is providing us an exciting opportunity to watch over the next few years as a very young star goes through the early stages of its formation,” said Carlos Carrasco-Gonzalez of the Center of Radioastronomy and Astrophysics of the National Autonomous University of Mexico in a statement.

The 1996 image depicts a compact region of hot, ionized wind coming from the young star. The 2014 image shows the wind shifting to a elongated outflow.

According to models, the young star is forming in an environment of dense gas surrounded by a dusty torus. In the early years the star will eject hot-ionized wind for several years at a time. The material from that wind will form a shell around the star and later, when it hits the donut shaped dusty torus which will slow it.

“In the span of only 18 years, we’ve seen exactly what we predicted,” Carrasco-Gonzalez said.

According to estimates, W75N(B)-VLA 2 is about eight times more massive than the sun. There are existing theoretical models which explain why nearly spherical outflows exist in young stars more massive than the sun. Uniform outflows are expected in young stars in the first few thousand years which is believed to be the age of W75N(B)-VLA 2.

“Our understanding of how massive young stars develop is much less complete than our understanding of how Sun-like stars develop. It’s going to be really great to be able to watch one as it changes. We expect to learn a lot from this object,” said Carrasco-Gonzalez.

Over time researchers will be able to continue watching this star develop and there is little doubt that it will not be the last. As an increasing number of powerful telescope come online and the collection of images and other data continues to grow, scientists will find other objects and phenomenon that they can watch evolve over time.

This will allow for theoretical models and predictions to be tested by reality.