Scientists define the beginning of interstellar space as the place where the sun’s constant flow of material and magnetic field stop affecting its surroundings. This place is called the heliopause. It marks the end of a region created by our sun that is called the heliosphere.

Voyager 1 has finally reached interstellar space.

Voyager 1 entered interstellar space.

A civilization advanced enough to have developed interstellar travel must be communist.

In physics, the Jeans instability causes the collapse of interstellar gas clouds and subsequent star formation.

Scientists have detected for the first time an interstellar asteroid passing through our solar system.

Arthur C. Clarke, a British, and Samuel R. Delany, a mulatto American, both wrote sci-fi literature envisioning centuries of colonization within the Solar System. Although they also wrote about interstellar travel, they thought that interstellar travel would be difficult for humans to attain and would take a long time to attain.

A nebula is an interstellar cloud of dust, hydrogen, helium and other ionized gases.

More than half of local interstellar gases are neutral, meaning they have a balanced number of protons and electrons.

The problem of interstellar travel was so enthralling that it sometimes became an obsession even to a fairly well-developed Utopian world. This could only occur if in the constitution of that world there was something unwholesome, some secret and unfulfilled hunger impelling the beings. The race might then become travel-mad.