2017 Planetary Motions

2017 PLANETARY MOTIONS (all dates formulated with UTC time)

MERCURY: (highest point 25 degrees) (88 day orbit)

January 19: Greatest Western Elongation (25d W) (Seen in the EAST as a Morning star)

February 07: Aphelion (0.46 AU)

March 07: Superior Conjunction (Opposite the Sun from Earth & beginning apparition)

March 23: Perihelion (0.30 AU)

April 01: Greatest Eastern Elongation (19d E) (Seen in the WEST as an Evening star)

April 20: Inferior Conjunction

May 06: Aphelion (0.46 AU)

May 17: Greatest Western Elongation (25d W)

June 19: Perihelion (0.30 AU)

June 21: Superior Conjunction

July 30: Greatest Eastern Elongation (27d E)

August 02: Aphelion (0.46 AU)

August 26: Inferior Conjunction

September 12: Greatest Western Elongation (17d W)

September 15: Perihelion (0.30 AU)

October 08: Superior Conjunction

October 29: Aphelion (0.46 AU)

November 24: Greatest Eastern Elongation (22d E)

December 12: Perihelion (0.30 AU)

December 13: Inferior Conjunction




VENUS: (highest point 47 degrees) (225 day orbit)

January 12: Greatest Eastern Elongation (47deg W)

February 17: Greatest Brilliancy (apparent magnitude -4.6)

February 20: Perihelion (0.72 AU)

March 25 – Inferior Conjunction

April 29: Greatest Brilliancy (apparent magnitude -4.5)

June 03: Greatest Western Elongation (-45deg E)

June 12: Aphelion (0.72 AU)

October 03: Perihelion (0.71 AU)




EARTH: (Random Data): (365 day orbit)

January 04: Perihelion: Closest that the Earth gets to the Sun in its orbit (0.98 AU)

February 03: Imbolic Cross Quarter

March 12: Spring Forward (Daylight Savings begins on Sunday at 02:00)

March 20: Vernal Equinox (equal day/night)

March 20: Astronomical spring begins and winter ends (Mar 20- June 20)

May 05: Beltaine Cross Quarter

May 26: Closest Perigee (357,209 km)

June 20: Astronomical spring ends and summer begins (June 20- Sept 22)

June 21: Summer Solstice, longest day & highest “Solar Noon” (Northern Hemisphere).

July 03: Aphelion: Earth’s furthest point from the Sun in its orbit (1.02 AU)

August 07: Lughnasad Cross Quarter

August 30: Closest Apogee (404,305 km)

September 13: Furthest Perigee (369,855 km)

September 22: Autumnal Equinox (equal day/night)

September 22: Astronomical summer ends and fall begins (September 22 – December 21)

November 05: Fall Back (Daylight Savings ends at Sunday at 02:00)

November 07: Samhain Cross Quarter

December 19: Furthest Apogee (406,604 km)

December 21: Astronomical fall ends and winter begins (Dec 21 – Mar 20)

December 22: Winter Solstice, shortest day & lowest “Solar Noon” (Northern Hemisphere)


MARS: (687 day orbit)

July 27: Conjunction

October 07: Aphelion (1.66 AU)




VESTA (4 Vesta): (1,325 day or 3.63 year orbit)

January 21: Opposition



CERES (1 Ceres): (1,680 day or 4.6 year orbit)

June 06: Conjunction



JUPITER: (12 year orbit)

January 12: Western Quadrature

February 06: Stationary

February 17: Aphelion (5.45 AU)

April 07: Opposition

June 10: Stationary

July 06: Eastern Quadrature

October 26: Conjunction




SATURN: (29 year orbit)

March 17: Western Quadrature

April 06: Stationary

June 15: Opposition

August 25: Stationary

September 14: Eastern Quadrature

December 21: Conjunction



URANUS: (84 year orbit)

January 10: Eastern Quadrature

April 14: Conjunction

July 21: Western Quadrature

August 03: Stationary

October 19: Opposition




NEPTUNE: (165 year orbit)

March 02: Conjunction

June 04: Western Quadrature

June 16: Stationary

September 05: Opposition

November 22: Stationary

December 03: Eastern Quadrature




PLUTO: (248 year orbit)

January 07: Conjunction

July 10: Opposition





Perihelion: An objects closest approach to the Sun in its orbit.

Aphelion: An objects furthest point from the Sun in its orbit.

Perigee: An objects closest point to Earth in its orbit (Moon).

Apogee: An objects furthest point from Earth in its orbit (Moon).

Inferior Planet: Planets inside Earth’s orbit (Mercury & Venus).

Superior Planet: Planets outside Earth’s orbit (Mars, Jupiter, Saturn, Uranus & Neptune).

Terrestrial Planets: The four (4) rocky planets of the inner solar system (Mercury, Venus, Earth & Mars).

Jovian Planets: The four (4) gas giant planets of the outer solar system (Jupiter, Saturn, Uranus & Neptune).

Ice Giants: The extremely cold gas giants of the outer solar system (Uranus & Neptune).

Superior Conjunction: When an inferior (inner) planet is opposite the Sun from Earth (elongation of 0 degrees).

Inferior Conjunction: When an inferior (inner) planet is directly between the Sun & Earth (similar idea as the new moon) (elongation of 0 degrees).

Conjunction: When a superior (outer) planet is opposite the Sun from Earth (elongation of 0 degrees).

Opposition: When a superior (outer) planet is opposite the Earth from the Sun’s vantage point so on Earth we see it as a full disk. This is similar to when the Moon is full, its fully illuminated (elongation of 180 degrees).

Apparition: When a planet comes out from behind the Sun = superior conjunction (inner planets) or conjunction (outer planets) and begins to grow in apparent size as it heads toward inferior conjunction (inner planets) and opposition (outer planets).

Greatest Eastern Elongation: When an inferior planet comes out of superior conjunction it’s seen in the western sky after sunset. Its highest point is its greatest eastern elongation.

Greatest Western Elongation: When a planet comes out of inferior conjunction it’s seen in the eastern sky before sunrise. Its highest point on the sky is its greatest western elongation.

Eastern Quadrature: When superior (outer) planets are at an elongation of 90 degrees east of the Sun as viewed from Earth.

Western Quadrature: When superior (outer) planets are at an elongation of 90 degrees west of the Sun as viewed from Earth.

Stationary: When retrograde motion of an outer planet begins and ends & when an inferior planet reaches greatest Western or Eastern elongation. Its apparent motion on the sky becomes “stationary” momentarily.

Retrograde: When a superior (outer) planet appears to be moving backward on the night sky. This happens when Earth catches up to an outer planet and passes it on the inside.

Prograde: After the Earth has completed its pass of the superior (outer) planet its motion reassumes its normal direction of travel which for all planets is called prograde or direct motion.

Waxing: When the Moon or planet’s disk is growing in illumination from new up to full phase.

Waning: When the Moon or planet’s disk is decreasing in illumination from full to new.

Crescent: When the disk of the Moon or planet is less than 50% illuminated.

Gibbous: When the disk of the Moon or planet is more than 50% illuminated.

Solstice: (Summer & Winter) When Earth’s tilt is at its maximum twice annually creating the longest night in the winter and longest day in the summer.

Equinox: (Spring & Fall) When the Earth’s tilt is positioned twice annually to deliver equal day & night.

Cross Quarter: Markers mid-way between each of the Equinoxes & Solstices. All combined; the Equinoxes, Solstices and Cross Quarters create 8 markers throughout the year.

Celestial Phenomena: (Quadratures, oppositions, conjunctions etc.): http://eco.mtk.nao.ac.jp/cgi-bin/koyomi/cande/phenomena_en.cgi

British Astronomical Association (Computing section): http://britastro.org/computing/charts_asteroid.html

Major Solar System events in 2016: http://www.astropixels.com/ephemeris/astrocal/astrocal2016gmt.html

Planetary Aspects: http://cseligman.com/text/sky/aspects.htm

NMSU Planetary aspects page: http://astronomy.nmsu.edu/nicole/teaching/ASTR505/lectures/lecture08/slide09.html

Naked Eye Planets: http://www.nakedeyeplanets.com/

In-The-Sky: http://in-the-sky.org/newsindex.php?feed=outerplanets

TimeAndDate sunset/sunrise: http://www.timeanddate.com/worldclock/sunrise.html

USN sunrise/sunset: http://aa.usno.navy.mil/data/docs/RS_OneYear.php