---
source: https://iinventedlight.com/library/notes/neptune-basics.md
title: "Neptune basics: the farthest planet"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source_license: "US government work, public domain; restated in our own words"
attribution: "Summary by iinventedlight (AI-assisted). Sources: NASA, Neptune: Facts, US government work, public domain; NASA, Neptune, US government work, public domain."
author: "iinventedlight (synthesis of cited sources); text drafted with AI assistance"
date: 2026-11-04
status: published
checked_on: 2026-11-04
as_of: 2026-11-04
confidence: medium
untested: "No observation or experiment was done; only the fetched government pages were read."
category: coverage-gaps
topic_area: "science-explain: astronomy and space"
tags: science, astronomy, neptune, planets
sources:
  - id: S1
    title: "Neptune: Facts"
    publisher: NASA
    url: https://science.nasa.gov/neptune/neptune-facts/
    accessed: 2026-11-04
    license: "US government work, public domain"
  - id: S2
    title: "Neptune"
    publisher: NASA
    url: https://science.nasa.gov/neptune/
    accessed: 2026-11-04
    license: "US government work, public domain"
---
# Neptune basics: the farthest planet

## Short answer
Neptune is the eighth and most distant planet from the Sun, an ice giant more than 30 times as far from the Sun as Earth. It cannot be seen with the naked eye, and it was the first planet found by math rather than by looking. [S1][S2]

## Key points
- It is dark, cold and swept by supersonic winds. [S1]
- One orbit takes about 165 years; it finished its first orbit since discovery in 2011. [S1]
- Voyager 2 is the only spacecraft to fly by it, in 1989. [S1]

## Claims
- id: C1
  claim: Neptune is the eighth and most distant planet.
  source: S1
  evidence: "Neptune is the eighth and most distant planet in our solar system."
- id: C2
  claim: Neptune was the first planet located using math.
  source: S2
  evidence: "Neptune was the first planet located using math."
- id: C3
  claim: Neptune completed its first 165-year orbit since discovery in 2011.
  source: S1
  evidence: "In 2011 Neptune completed its first 165-year orbit since its discovery in 1846."
- id: C4
  claim: Voyager 2 was the first spacecraft to fly by Neptune.
  source: S2
  evidence: "It was the first spacecraft to fly by the planet."

## Sources
- [S1] Neptune: Facts. NASA. https://science.nasa.gov/neptune/neptune-facts/ . License: US government work, public domain. Accessed 2026-11-04.
- [S2] Neptune. NASA. https://science.nasa.gov/neptune/ . License: US government work, public domain. Accessed 2026-11-04.

License: this note is CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Summary by iinventedlight (AI-assisted).