Australian amateur astronomer Terry Lovejoy first spotted comet Lovejoy (C/2014 Q2) in August, 2014, when it was cruising past Jupiter. Then, you could only view it through large telescopes. Now, it's bright enough that many of us will be able to see it even in U.S. and European cities, with the naked eye.
The comet casts a greenish light, and is traveling through our inner solar system for the first time in more than 11,000 years.
From National Geographic:
To the delight of sky-watchers, the comet has quickly brightened in the Northern Hemisphere's skies since the December holidays, on its way to reaching its expected mid-January peak.
That increase in brightness has come now despite the comet making its closest approach to Earth on January 7, when it was about 44 million miles (70 million kilometers) from Earth. That is roughly half the distance separating our planet from the sun.
Lovejoy now shines at an estimated magnitude 3.8, making it an easy target for binoculars within city limits. It is even visible as a faint, fuzzy ball of light to the naked eyes from the dark countryside.