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 30 or 40 minutes 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. The Sun is in Aquarius and a number of planets and bright stars will be above the horizon for observers within the umbral path. Figure 8 depicts the appearance of the sky during totality as seen from the center line at 1:00 UT. This corresponds to eastern Russia near the northeast border of Mongolia. Venus is the brightest planet and can actually be observed in broad daylight provided that the sky is cloud free and of high transparency (i.e. - no dust or particulates). During the 1997 eclipse, Venus is located 6° west of the Sun and is rapidly approaching superior conjunction at month's end. Look for the planet during the partial phases by first covering the crescent Sun with an extended hand. During totality, it will be impossible to miss Venus since it shines at a magnitude of mv=-3.4. Although two magnitudes fainter at mv=-1.3, Mercury will also be well placed just 3° west of the Sun. In fact, Mercury passes superior conjunction two days after the eclipse. Together, Venus and Mercury should form a striking pair during totality. Jupiter will be another prominent planet located 38° west of the Sun and shining at mv=-1.5. Under good conditions, it may be possible to spot Jupiter 5 to 10 minutes before totality. Finally, Saturn is located 19° east of the Sun at mv=+0.4, making it the most difficult planet to spot. Mars is just past opposition and will be below the horizon during the eclipse. A number of the brightest summer stars may also be visible during totality. The summer triangle composed of Altair (mv=+0.77), Deneb (mv=+1.25), and Vega (mv=+0.03), will be nearly overhead to the south. Twenty degrees above the western horizon lies Arcturus (mv=-0.04), while Capella (mv=+0.08) stands twelve degrees high to the north northeast.

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), V is the apparent visual magnitude of the planet, and Elong gives the solar elongation or angle between the Sun and planet. Note that Mars is near opposition and will be below the horizon for all observers during the eclipse.

Note: This is an HTML 3.0 table. The HTML 3.0 table directives are currently (1995 August 1) supported by Netscape and Agena (at least), but not by Mosaic (for example). A text version of this table is also available for the Web-viewer-challenged.
Planetary Ephemeris: 1997 Mar 9, 01:00 UT
Equinox = Mean Date
Sun23h17m42s-04°32´53" 0.99290-26.71933.0
Mercury23h11m43s-07°08´50" 1.36922-1.04.9 1.003.0W
Venus22h57m00s-08°14´21" 1.70648-3.49.8 0.996.3W
Mars12h05m45s+03°30´40" 0.67434-1.013.9 1.00168.0W
Jupiter20h52m27s-18°01´41" 5.85974-1.533.6 1.0038.0W
Saturn00h31m09s+00°58´27" 10.383750.415.9 1.0019.2E

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