When I consider thy heavens, the work of thy fingers, the moon and the stars, which thou hast ordained (Psalm 8:3).
Comets are fascinating things. Although there are a lot of them out there in our night sky, the overwhelming majority of them are insufficiently bright to see with the naked eye. But every so often, a comet appears, which is bright enough to see during the night, and sometimes bright enough even to see during the day.
The most notable comet that I can remember was Comet Hale-Bopp, which was visible in April 1997. At the time, I was a Head of Science in a state-run school in South Wales. The comet was clearly visible from my classroom laboratory, at the end of the school day, and was a fascinating sight for my students.
The comet's tail is not caused by the object's movement, along its highly elongated, elliptical orbit around the sun. Instead, it is caused by particles from the sun - the so-called solar wind - blowing material away from the comet, as it evaporates, when it is closer to the sun. Every time a comet approaches the sun, it gets a little smaller.
It is not difficult, therefore, to calculate how long a comet can last. It is not possible for it to last more than about 10,000 years. But secular astrophysicists suggest that comets were formed at the same time as the rest of the Solar System. Such scientists cannot accept this age, as it is less than the 4.5 billion years required for their theory. Biblical creationists have no such difficulty, as the Bible gives a timescale of only 6,000 years.