As Comet Leonard is traveling closer to Earth on its way to the sun, it appears to be losing its brightness. While the comet does look brighter as it approaches our planet, it is in fact getting dimmer and that is a mystery.
In an interview with Space.com, Quanzhi Ye, who is an astronomer at the University of Maryland and who specializes in comets, reiterated this by saying, “It's not great news. The comet should be brighter and brighter.” “If it's not getting brighter then something's wrong, but we don't know exactly what at this stage.”
While it’s unclear as to why it’s dimming, one possibility is that it is on the verge of breaking apart which is what has happened to several other comets in the past that were on their way to the sun. “Why it's fading, there are all kinds of hypotheses,” Ye noted, adding, “The simplest and the most obvious one is something unhealthy is happening to the comet.”
Even though it continues to dim, the good news is that it is still intact – at least for now. It will make its closest approach to Earth on December 12th and will be closest to the sun on January 3rd (this is called perihelion).
For those wishing to catch a glimpse of Comet Leonard, Ye said that even if it is on the verge of falling apart, there will be a good chance of spotting it, “Usually it will take a few days before you can see the comet dramatically change and fade and stuff.” “We should be still in for something pretty bright next week, simply because it takes time for the comet to fully disintegrate.”
Sky watchers will be able to view the comet in the late mornings through December 12th. It won’t be visible for several days due to the glare of the sun before re-appearing again in the evening by December 17th.
But as for its future, nobody really knows, as Ye explained, “Comets do all sorts of weird things.” “Sometimes they disintegrate before reaching perihelion, sometimes after, and there are even hypotheses saying that comets can disintegrate when they're farther out from the sun. So we won't know until we see it happen.”
There are numerous reasons as to why comets break apart, such as gravitational tugs from a planet or the sun; as well as excessive spinning caused by the comet’s materials vaporizing.
A picture of Comet Leonard can be seen here.