What region of space begins at 50,000 AU from the Sun and extends halfway to the nearest star?

The region of space that begins at 50,000 astronomical units (AU) from the Sun and extends halfway to the nearest star is known as the Oort Cloud. This hypothetical cloud of icy bodies surrounds the solar system and is believed to be the source of long-period comets. It is estimated that the Oort Cloud may extend to about 100,000 AU, with the halfway point to the nearest star (Proxima Centauri, located about 4.24 light years away) being roughly around that distance.

The Oort Cloud is significant in understanding the outer solar system as it represents a boundary for the influence of the Sun's gravity and serves as a reservoir of ancient materials from the formation of our planetary system. The composition of the Oort Cloud is primarily icy objects, which play a role in the dynamic processes that lead to cometary activity.

The other options refer to different concepts unrelated to this specific distance from the Sun. The Oort Comet is not a recognized region but rather a term that could confuse those with knowledge of comets originating from the Oort Cloud. An elliptical orbit refers to the shape of an orbit, particularly of planets or celestial bodies, gaining no relevance in the context of the regions of space discussed.