Scientists may have found a moon orbiting around an exoplanet called Kepler-1625b.

Interstellar space is under keen observation these days following a surge of missions from different space agencies around the globe. The idea of finding an alternative habitat for humanity has become increasingly famous and many super-powers of the world including the United States and Russia are in a race to achieve this feat first. Similarly, the intentions of the European Space Agency are quite clear in this regard. The space telescopes of NASA (Kepler and Hubble) have made some amazing discoveries about interstellar space and we might have a massive addition to this list.

According to the latest announcement from the space agency, astronomers may discover the first interstellar moon as they found tantalizing evidence for that. This celestial object (potentially a moon) lies in the Cygnus Constellation at a distance of 8000 light-years from the Earth and is orbiting Kepler-1625, a gas-giant planet. The authorities at NASA explained that this hypothesis is tentative and they will need the observations of Hubble to make a conclusive decision. Thomas Zurbuchen, an Associate Administrator of Science Mission Directorate at NASA clarified about it by saying,

“This intriguing finding shows how NASA’s missions work together to uncover incredible mysteries in our cosmos. If confirmed, this finding could completely shake up our understanding of how moons are formed and what they can be made of.”

Exomoons cannot be pictured directly, just like exoplanets, and we need to infer their presence from the dimming of the light of their host star as they pass in front of it. The name given to this event is ‘Transit’ and it has proved extremely beneficial in the detection of many exoplanets. Having said that, exomoons are harder to detect because they are much smaller than their companion planets. Consequently, their transit signals are much weaker when plotted on a light curve. Light curve measures the duration of the celestial body passing and the amount of momentary dimming. The rotation of the moon around the planet makes it even harder as the position of exomoons changes continuously.

David Kipping joined forces with Alex Teachey (both of these astronomers belong to the Columbia University in New York) and examined 284 exoplanets discovered by the Kepler Space Telescope. They chose those planets who had at least 30-days orbit around their host star. One of these planets called Kepler-1625b suggested the presence of a moon through its transit signal. Kipping mentioned that in the following words:

“We saw little deviations and wobbles in the light curve that caught our attention.”

Once they were convinced that an exomoon could be there, the researchers used Hubble for detailed observations. They used this revolutionary telescope for 40 hours to obtain more precise data on the dimming of light. Kepler-1625b was monitored continuously before and during its 19-hour transit across its host star. After the commencement of this transit, Hubble detected another decrement in the star’s brightness approximately 3.5 hours later but it was much smaller than the first. Scientists observed that the small decrease is consistent with a gravitationally-bound moon trailing the planet. Unfortunately, they couldn’t analyze the complete transit of the potential exomoon as the scheduled Hubble observations ended before that.

The fact that the transit of Kepler-1625b occurred an hour earlier than predicted also favors the idea of an exomoon orbiting around it. This is pretty much similar to Earth because our planet shares the common center of gravity with our Moon which allows it to wobble from its predicted location. However, the researching team did mention that the gravitational pull of another planet could have led to this planetary wobble but Kepler hasn’t found any other planet in this system, yet. Kipping acknowledged that in addition to delight, it was quite shocking to see the second dip. He said,

“A companion moon is the simplest and most natural explanation for the second dip in the light curve and the orbit-timing deviation. It was definitely a shocking moment to see that Hubble light curve, my heart started beating a little faster as I kept looking at that signature. But we knew our job was to keep a level head and essentially assume it was bogus, testing every conceivable way in which the data could be tricking us.”