  This is a translation from Latin of E840 'De motu cometarum in orbitis
parabolicis, solem in foco habentibus', in which Euler addresses six problems
related to comets in heliocentric parabolic orbits. Problem 1: Find the true
anomaly of a heliocentric comet from the latus rectum of the orbit and the
medium Earth to Sun distance. Problem 2: Find the orbit of a heliocentric comet
from three given positions. Problem 3: Knowing the orbit of a comet, and the
instant in time in which it dwells in the perihelion, define its longitude and
latitude at any time. Problem 4: From two locations of a heliocentric comet,
find the inclination of the comet's orbit in relation to the ecliptic, and the
positions of the nodes. Problem 5: From the time before or after the comet had
reached the perihelion, and from the comet's distance to the perihelion as seen
from the Sun, find the same distance in another time before or after it had
appeared in the perihelion. Problem 6: Find the orbit of a comet from three
given heliocentric longitudes and latitudes. From these problems, several
corollaries and scholia are derived.

History and Philosophy of Physics;Earth and Planetary Astrophysics