perihelion

Closest solar approach

Perihelion is the point in a planet's or comet's orbit when it is closest to the sun.

Earth reaches perihelion in early January, counterintuitively during Northern Hemisphere winter.

The opposite point—farthest from the sun—is aphelion.

The comet will reach perihelion next month.

orbital

eccentricity

Unconventional behavior or nature

ellipseConic section curve
fociCentral points of convergence
closest approachMinimum separation between objects

velocity · gravitational pull · trajectory · precession · inclination · nodes · anomaly · elliptical orbit · orbital mechanics

astronomical

solar radiation

Energy emitted by sun

solar windContinuous stellar particle emission
comet tailLuminous debris wake
transitMovement between places

insolation · astronomical unit · Icarus · Mercury · inner planets · solar heating · brightening

geometric

point

Exact location or meaning

axisRotation reference line
radiusCenter-to-perimeter distance
distanceSpace between two points

center · vertex · node · major axis · minor axis · focal point · pericenter · apocenter · conic section · curve

Categories

astronomystars, moon, sun, planet, planets
solar systemsun, Earth, Mars, Jupiter, Saturn
spacespace, sun, moon, stars, star
gravitygravity, graviton, gravity well, gravitational pull, gravity wave
celestial cycleslunar cycle, solar cycle, lunar phase, orbit, eclipse
orbit termsellipse, trajectory, satellite, revolution, rotation

Opposites

orbital distance from the Sun

perihelionaphelion

Farthest point from sun

apogee · apocenter

Family

helium, helios, apogee, peri, perigee, aphelion, heliograph, heliocentric, heliocentrism

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