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Not every near-earth asteroid is a threat. NASA applies three hard thresholds -

More than a million asteroids live in the main belt between Mars and Jupiter. A

Of the thousands of catalogued comets, most live far beyond Neptune and only dip

Every SpaceAtlas orbital record carries a quality flag and an observation count.

Asteroids and comets move on ellipses, and every ellipse can be pinned down by j

The four families of near-Earth asteroids - Apollo, Amor, Atira and Aten - are d

A worked example: take one real object, follow each column of its orbital record

The line between asteroid, comet and meteoroid is blurrier than most people expe

Orbital elements are not measured directly - they are solved for from a scatter

Absolute magnitude H is the single most useful proxy for an asteroid's size - wh