Sky at Totality

The total phase of an eclipse is accompanied by the onset of a rapidly darkening sky whose appearance resembles evening twilight about half an hour after sunset. The effect presents an excellent opportunity to view planets and bright stars in the daytime sky. Aside from the sheer novelty of it, such observations are useful in gauging the apparent sky brightness and transparency during totality. During the total solar eclipse of 2002, the Sun is in southern Ophiuchus. Depending on the geographic location, as many as four naked eye planets and a number of bright stars will be above the horizon within the umbral path. Figure 24 depicts the appearance of the sky during totality as seen from the center line at 06:15 UT. This corresponds to western Zimbabwe near the Botswana border.

The most conspicuous planet visible during totality will be Venus (m_v = -4.5) located 39° west of the Sun in Virgo. Mars (m_v=+1.7) is one and a half degrees west of Venus, but offers a much more difficult target since it will be nearly 500 times fainter. From Zimbabwe, the pair will appear 70° high in the northeast. Compared to Venus, Jupiter (m_v = -2.2) is the next brightest planet but it will be located in the northwestern sky 114° away from the Sun. None of these planets will be visible from Australia since they all set hours before totality begins. However, Mercury (m_v = -0.6) should be discernible from most places along the eclipse track. The innermost planet lies 11° east of the Sun. Since it is nearly at opposition, Saturn (m_v = -0.1) will be below the horizon for most locations along the umbral path.

A number of the bright stars may also be visible during totality. Antares (m_v = +1.06) is 5° south of the Sun while Arcturus (m_v = -0.05) stands 55° to the northwest. Spica (m_v = +0.98) lies 10° west of Venus and Mars. Finally, the great southern stars Alpha (m_v = +0.14) and Beta (m_v = +0.58) Centauri are 45° south of the Sun. Star visibility requires a very dark and cloud free sky during totality. The following ephemeris [using Bretagnon and Simon, 1986] gives the positions of the naked eye planets during the eclipse. Delta is the distance of the planet from Earth (A.U.'s), App. Mag. is the apparent visual magnitude of the planet, and Solar Elong gives the elongation or angle between the Sun and planet.

Ephemeris: 2002 Dec 04 08:00:00 UT
Equinox = Mean Date

Object RA Dec Delta V Apparent
Diameter (") Phase Solar
Elong (°)
Sun 16h42m47s -22°13'39" 0.98565 -26.7 1947.2
Moon 06h03m27s -22°35'01" 0.00244 15.4 1962.8 0.00 0.4E
Mercury 17h29m23s -25°14'21" 1.37356 -0.6 4.9 0.95 11.3E
Venus 14h06m16s -11°02'06" 0.39903 -4.5 41.8 0.24 38.8W
Mars 13h59m38s -11°16'06" 2.26296 1.7 4.1 0.96 40.2W
Jupiter 09h23m00s +16°02'32" 4.81623 -2.2 40.9 0.99 113.9W
Saturn 05h45m41s +22°04'08" 8.07966 -0.1 20.6 1.00 165.2W

Object	RA	Dec	Delta	V	Apparent Diameter (")	Phase	Solar Elong (°)
Sun	16h42m47s	-22°13'39"	0.98565	-26.7	1947.2
Moon	06h03m27s	-22°35'01"	0.00244	15.4	1962.8	0.00	0.4E
Mercury	17h29m23s	-25°14'21"	1.37356	-0.6	4.9	0.95	11.3E
Venus	14h06m16s	-11°02'06"	0.39903	-4.5	41.8	0.24	38.8W
Mars	13h59m38s	-11°16'06"	2.26296	1.7	4.1	0.96	40.2W
Jupiter	09h23m00s	+16°02'32"	4.81623	-2.2	40.9	0.99	113.9W
Saturn	05h45m41s	+22°04'08"	8.07966	-0.1	20.6	1.00	165.2W

For a map of the sky during totality from Australia, see the special web site for the total solar eclipse of 2002 December 4.

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