Interior Asteroids

139 asteroids have orbits that lie entirely within Earth’s aphelion distance from the Sun (1.016725 AU). That number reduces to 50 inside Earth’s semimajor axis distance (1.000001 AU). That number further reduces to 26 inside Earth’s perihelion distance (0.983277 AU). Those 26 asteroids are listed below.

Only one asteroid lies entirely within Venus’s orbit (2020 AV2), and none are known inside Mercury’s orbit…so far. Asteroids inside of the Earth’s orbit are extremely difficult to detect since their angular distance from the Sun is never very large, and the glare of the Sun interferes. This is especially true for any asteroids that might exist inside of Mercury’s orbit.

An asteroid is given a provisional designation when it is discovered that begins with the year of discovery. After the orbit of the asteroid has been sufficiently well-determined, it is given a number. Then, eventually, the numbered asteroid is given a name.

Only 6 of the 26 asteroids entirely within Earth’s perihelion distance have received numbers, and only one of these has been given a name: Atira.

Interestingly, 12 of these 26 asteroids have been discovered since 2017, including 4 so far this year.

In the table below, i is the orbital inclination relative to the ecliptic plane, e is the orbital eccentricity, q is the perihelion distance, a is the semimajor axis distance, Q is the aphelion distance, and P is the orbital period. The table is listed in order of aphelion distance, smallest to largest.


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