a large lump of rock that is heading for a planet
Halley's Comet is most probably a collection of ice, dust and rocks; a "dirty snowball" may be the most apt description. I'm not sure that "land" would fit the description.
Need a detalied description of all markings to answer.
No. That description most closely matches a comet.
That description fits a comet. Comets are made up of ice, dust, and rock, and they have long, elliptical orbits around the Sun.
That sounds like the description of a comet. However, please note that comets ONLY have a tail when they are close to the Sun. During most of their orbit, they are too far away from the Sun to have a tail.
a comet/meteorite
It is a comet.
That sketchy description could be applied to a planet, a satellite, a moon, an asteroid, a comet, a meteoroid, or even an electron.
Halley's Comet
This description matches that of a comet. Comets are composed of ice, rock, dust, and frozen gases, and form a glowing coma and tail when they approach the Sun due to the heating and outgassing of these volatile components.
The comet's tail is in front of the comet, not after
=The reindeer who's name is also the name of a kitchen cleanser is COMET=