labes
- landslide.
- labyrinthus
- intersecting valley complex.
- lacus
- lake.
- Lagrange, Joseph Louis
1736-1813
- French (originally Italian, Giuseppe Luigi
Lagrangia; born in Turin, moved to Paris and
became a French citizen) mathematician and
astronomer; made a number of contributions to the
study of celestial mechanics.
- Lagrange points
- Lagrange showed that three bodies can lie at the
apexes of an equilateral triangle which rotates
in its plane. If one of the bodies is
sufficiently massive compared with the other two,
then the triangular configuration is apparently
stable. Bodies at such points are sometimes
refered to as Trojans.
The leading apex of the triangle is known as the
leading Lagrange point or L4; the trailing apex
is the trailing Lagrange point or L5. The
colinear with the other two bodies are the L1, L2
and L3 unstable equilibrium points which can
sometimes be useful places for spacecraft, eg
SOHO.
- Lassell, William
1799-1880
- British astronomer, discovered Neptune's largest
satellite, Triton and (with Bond)
discovered Saturn's
moon Hyperion. A successful brewer before turning
to astronomy.
- Le Verrier, Urbain Jean
Joseph 1811-1877
- French mathematician whose prediction of the
position of an undiscovered planet (Neptune) that
caused perturbations in the orbit of Uranus was the
first to be confirmed (by Galle)
though Adams had made a
similar but unpublished prediction some months
earlier.
- lidar
- an instrument similar to radar that operates at
visible wavelengths.
- limb
- the outer edge of the apparent disk of a celestial body
- light-year
- = 9.46053e12 km (= 5,880,000,000,000 miles =
63,239 AU); the distance traveled by light in a
year.
- linea
- elongate marking.
- liter
- = 1000 cm3 = 1.06 US quarts
- Lowell, Percival
1855-1916.
- American astronomer. He founded the Lowell
Observatory in Arizona (1894), where his studies
of Mars led him
to believe that the linear markings (first noted
by Schiaparelli)
on the surface were "canals" and
therefore that the planet was inhabited by
intelligent beings. His successors later
discovered Pluto.
- lunar month
- The average time between successive new or full
moons, equal to 29 days 12 hours 44 minutes. Also
called synodic month.
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