PLANET VISIBILITY
2020 – 2021 The following diagrams show, in graphical form, when the five “naked-eye” planets Mercury, Venus, Mars, Jupiter and Saturn are visible in the night sky during the period July 2020 – June 2021. Each diagram spans the hours of darkness, covering the period from 16:00 to 08:00 with midnight being represented by the central line across the diagram. For a given date, time runs from the bottom to the top of the diagram. Times are shown in terms of New Zealand Standard Time; one hour must be added when New Zealand Daylight Time is in force. Each diagram is plotted for Wellington; time differences at other locations in New Zealand will generally not exceed an hour. In addition to the planet information, the diagrams show the time of sunset and sunrise as well as the end and start of astronomical twilight which is the time when the Sun is 18° below the horizon. The shaded area of each diagram indicates the range of dates/times that the planet is visible in the night sky.
Appearance of the planets Unless they are near to the horizon, planets can be distinguished from the twinkling stars by their more steady appearance. Twinkling is caused by turbulence in the atmosphere which has a greater effect on the light coming from
ASTRONOMICAL point sources (stars) than on the light from much closer planets which are not point sources. Another pointer to identifying planets is that they are usually one of the brightest of the objects in the night sky. Mercury is the most difficult to see of the bright planets; due to its close proximity to the Sun it is seldom seen in fully dark skies. Venus is readily identified by its brightness – being exceeded by only the Sun and Moon. Venus is often referred to as either the Evening Star (when visible in the west after sunset) or the Morning Star (in the east before sunrise). Mars is notable for its orange-red appearance and is popularly known as the Red Planet. Jupiter’s white light always outshines all of the stars whilst pale yellow Saturn is usually the least conspicuous of the five naked-eye planets.
MERCURY
08:00 08:00 M E R R S IS C 06:00 Y E E U 06:00 MERCUR IS S RY S R RIS S UNRISE Y E R U M C 04:00 ERC S R 04:00 URY RISE ME
TW 02:00 ILIGHT BEGINS 02:00
00:00 00:00
T ENDS ILIGH 22:00 TW 22:00 SETS ERCUR Y M Y S R E CU T ER S 20:00 M 20:00 NS SU ET
New Zealand Standard Time RY S New Zealand Standard Time RCU ET 18:00 ME S 18:00
16:00 16:00 Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
2020 2021
MERCURY is the most difficult of the bright planets to see as it always appears in close proximity to the Sun. This means it is visible only towards the horizon in the twilight sky. The best period to see Mercury in the morning sky will occur between mid-February and the end of March when the planet rises before twilight begins. Other morning appearances during July/August, November/December and late June are less favourable as Mercury rises during the dawn period. The best time to see Mercury in the evening will occur between mid-September and mid-October when it will set after twilight has ended. Other evening appearances during January and May are less favourable as Mercury sets before twilight ends. At the beginning of March Mercury will be less than 1° from brighter Jupiter.
16 ASTRONOMICAL INFORMATION | New Zealand Nautical Almanac 2020 – 21 VENUS
08:00 08:00
06:00 06:00 SUNRISE
04:00 VENUS RISES 04:00 S GIN T BE 02:00 TWILIGH 02:00
00:00 00:00
LIGHT ENDS 22:00 TWI 22:00
20:00 20:00 NS SU ET New Zealand Standard Time SETS New Zealand Standard Time 18:00 VENUS 18:00
16:00 16:00 Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun ASTRONOMICAL
2020 2021
VENUS will be visible as a bright object in the eastern sky until the end of September by which time it will rise at the beginning of twilight. From October to late March Venus will rise during twilight. Venus will then reappear in the western sky in twilight during April – June.
MARS
08:00 08:00
06:00 06:00 SUNRISE 04:00 04:00 S GIN BE HT 02:00 TWILIG 02:00
00:00 00:00
M MA ARS RS RIS SE 22:00 ES TS 22:00
20:00 20:00 T ENDS TWILIGH NS SU ET New Zealand Standard Time New Zealand Standard Time 18:00 18:00
16:00 16:00 Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
2020 2021
MARS will rise just before midnight at the beginning of July and progressively earlier in the evening until mid-October when the red planet will rise at sunset and be visible throughout the night. Thereafter Mars will set progressively earlier during the night, before midnight from mid-January and three hours after sunset until the end of June.
ASTRONOMICAL INFORMATION | New Zealand Nautical Almanac 2020 – 21 17 JUPITER
08:00 08:00
06:00 06:00 SUNRISE 04:00 04:00
J UP T J 02:00 IT WILIGHT BEGINS UP 02:00 ER ITE S R E RI TS SE 00:00 S 00:00
TW ILIG 22:00 HT 22:00 EN DS 20:00 20:00 SUNSET New Zealand Standard Time New Zealand Standard Time 18:00 18:00
16:00 16:00
ASTRONOMICAL Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
2020 2021
JUPITER will be visible throughout the night mid-July. The giant planet will then start setting during the early morning and then in the evening from mid-November. From mid-December Jupiter will set during twilight, becoming too close to the Sun during January. Jupiter will reappear in the eastern sky ahead of sunrise during February. By mid-May Jupiter will rise at midnight and mid-evening by the end of July.
SATURN
08:00 08:00
06:00 06:00 SUNRISE 04:00 04:00
TW ILIGH 02:00 SA T BEGINS S 02:00 TU AT R U N R S N ET RI S S 00:00 ES 00:00
TW ILIGH 22:00 T EN 22:00 DS 20:00 20:00 SUNSET
New Zealand Standard Time New Zealand Standard Time 18:00 18:00
16:00 16:00 Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun
2020 2021
SATURN will be visible throughout the night mid-July. The ringed planet will then start setting during the early morning and then in the evening from mid-November. From late December Saturn will set during twilight, becoming too close to the Sun over the following month. Saturn will then reappear in the eastern sky ahead of sunrise during February. By late April Saturn will rise at midnight and mid-evening by the end of July. Saturn will draw very close to brighter Jupiter during December.
18 ASTRONOMICAL INFORMATION | New Zealand Nautical Almanac 2020 – 21