To give a quantitative idea of just how dilute the matter in outer space is, consider that roughly 2.5 × 10¹⁹ particles, typically atoms, occupy 1 cm³ (1 mL) of volume in the Earth’s atmosphere. In outer space there is, on average, only one single particle in this same volume. Outer space is a much better vacuum than even the best vacuums ever created on Earth!