Light Years my star treck buddy.
because that was the first space craft to leave the solar system
the units used are light seconds, minutes, hours and astronomical units.
Not sure whether it is in any way more "useful", but a common unit of measurement for distances within the Solar System is the AU.SI units, especially meters and kilometers, are also used, though.
because that was the first space craft to leave the solar system
in the solar system, distances are measured in AU's which stand for atronomical units.
because that was the first space craft to leave the solar system
Nasa
scientists can use them to study the early solar system
Yes, it is. At 2006, the scientists decided that it was not a planet of solar system. Now, there are just eight planets in the solar system.
Scientists
to observe the solar system
N.a.s.a