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  1. What Are Neptunian Planets? - Science@NASA

    Oct 28, 2024 · Neptunian planets typically have hydrogen and helium-dominated atmospheres with cores of rock and heavier metals. Neptunian exoplanets are similar in size to Neptune or …

  2. Neptune - Science@NASA

    Apr 29, 2025 · Neptune is the eighth and most distant planet from the Sun. It’s the fourth largest, and the first planet discovered with math.

  3. Neptune: Facts - NASA Science

    Apr 21, 2025 · And Neptune makes a complete orbit around the Sun (a year in Neptunian time) in about 165 Earth years (60,190 Earth days). Sometimes Neptune is even farther from the Sun …

  4. Overview - NASA Science

    Mar 11, 2025 · Neptunian planets are similar in size to Neptune or Uranus in our solar system. They likely have a mixture of interior compositions, but all will have hydrogen and helium …

  5. Neptune Moons - NASA Science

    Mar 12, 2025 · Neptune has 16 known moons. The first moon found – Triton – was spotted on Oct. 10, 1846, just 17 days after Neptune was discovered.

  6. NASA’s Webb Reveals the Ancient Surfaces of Trans-Neptunian …

    Feb 12, 2025 · Trans-Neptunian objects (TNOs) are icy bodies ranging in size from Pluto and Eris (dwarf planets with diameters of about 1,500 miles) down to tens of miles (Arrokoth) and even …

  7. Kuiper Belt: Facts - NASA Science

    Mar 13, 2025 · While there are many icy bodies in this region that we broadly refer to as Kuiper Belt Objects (KBOs) or trans-Neptunian objects (TNOs), they're fairly diverse in size, shape, …

  8. Trans-Neptunian Object - NASA Science

    Sep 13, 2010 · This is an artist's concept of a craggy piece of solar system debris that belongs to a class of bodies called trans-Neptunian objects (TNOs). Most TNOs are small and faint, …

  9. Kuiper Belt - Science@NASA

    Mar 12, 2025 · The Kuiper Belt is a doughnut-shaped region of icy objects beyond the orbit of Neptune. It is home to Pluto and most of the known dwarf planets and some comets.

  10. Hypothetical Planet X - Science@NASA

    Mar 12, 2025 · Why these long-period orbits cluster in their orientations 3. Why the solar system hosts a distant population of highly inclined trans-Neptunian bodies 4. The existence of objects …