A. The next total solar eclipse will occur on 23 November 2003. The Moon's umbral shadow will "touch down" on the Earth at 22h24m Universal Time (U.T.) and "lift off" at 23h15m U.T.
A. On the long-term average, a total solar eclipse is visible somewhere in the world about once every sixteen months. However, the overlap between the "cycles" of solar eclipses is complex. The total solar eclipse before the 23 November 2003 eclipse occurred 11 months earlier, the next one (which has a maximum duration of the total phase of 42 seconds) will not happen until 08 April 2005. Also, on average, any given spot on the Earth will see a total solar eclipse about once every 360 years. However, eclipse paths can cross specific locations much more frequently (for example the 2001 and 2002 eclipse paths crossed in South Africa), an those living in the right location saw both of them.
A. Only in the Antarctic. The "path of totality", the region on the Earth's surface which will be swept by the Moon's umbral shadow and where the total phase of the eclipse can be seen, begins in the Antarctic (Great Southern) Ocean and traverses over part of the Antarctic. The eclipse will not be visible from land anywhere except over a small portion of Antarctica.
A. No.
A. No, but accessibility is difficult. Until this juncture in time (and technology) Antarctic eclipses have been elusive targets.
A. The eclipse geometries can be "unusual". For example, with this eclipse, the Moon's shadow passes "over the pole" before reaching the Earth. So, the eclipse occurs in the hemisphere of the Earth which is experiencing nighttime (except in the Antarctic region), and the path of totality advances across Antarctica opposite the direction of the Earth's rotation.
A. Our planned mid-eclipse intercept, when our Boeing 747-400 will be co-located in the center of the Moon's shadow, is at 22h 44m Universal Time. We remain flexible, and can intercept the shdow earlier in time (closer to the coast) or later (further inland) in the event of any obscuring cloud or turbulent air.
A. In the absence of any winds, totality, as seen from our aircraft with mid-eclipse at 22h 44m UT, will last 2m 35s.
A. It does. From the ground totality (at the location where mid-eclipse occurs at 22h44m U.T.) will last only 01m 59s, thirty-six seconds shorter than we will experience in our aircraft. Note that the difference is longer than the maximum duration of totality experienced during the last total solar eclipse from Australia on 04 December 2002, and is only 8 seconds shorter than the maximum duration of totality of the next, 04 April 2005 total solar eclipse, in the middle of the South Pacific Ocean.
A. Our true airspeed will be 470 nautical miles (870.5 kilometers per hour).
A. At the 22h 44m UT instant of mid-Eclipse the Moons' shadow will be moving at: 3,888.5 kilometers per hour (2,099.6 nautical miles per hour).
A. The aircraft will be moving with a speed of appx 22.4% of the lunar shadow (along its direction of motion at 22h 44m U.T.). Our aircraft will be moving almost in the same direction as the moon's shadow. Hence the shadow will overtake and pass us more slowly than an stationary observer on the ground.
A: For the following "baseline" flight parameters:
U.T. Intercept: 22:44:00
Flight Altitude: 38000ft
Heading:
198.72°
Air Speed: 470.0nm/h
Wind Speed:
0.0nm/h
Wind Direction:
0.0°
the circumstances of the total phase of the eclipse are as follows:
TOTALITY DURATION = 2m 34.7s
MID-ECLIPSE INTERCEPT:
LATITUDE = -69° 59' 15.0"S
LONGITUDE = +93° 05' 40.7"E
Solar Altitude = 15.0°
Solar Azimuth = 108.7°
SECOND CONTACT (START OF TOTALITY)
UNIVERSAL TIME
= 22:42:42.7
AIRCRAFT LATITUDE = -069°
49' 44.5''
AIRCRAFT LONGITUDE = +093° 15'
1.1''
Solar Altitude = +14.9°
Solar Azimuth = 108.9°
Position Angle of Contact = 109.3°
THIRD CONTACT (END OF TOTALITY)
UNIVERSAL TIME
= 22:45:17.4
AIRCRAFT LATITUDE = -070°
08' 52.9''
AIRCRAFT LONGITUDE = +092° 56' 13.0''
Solar Altitude = +15.1°
Solar Azimuth = 108.5°
Position Angle of Contact = 289.7°
Conditions in flight may call for a mid-eclipse intercept at a different altitude or Universal Time. For lower flight altitudes, at 22h 44m UT, the path of totality shifts anti-sunward (toward an azimuth of 288.7°) by approximately 4000 ft (2/3 nautical mile) for every 1000 ft of altitudes below 38,000 ft.
A. Strictly speaking, no, this occurs at a location corresponding to a mid-eclipse near 22h 49.2m U.T.
A. The maximum duration changes very little over this portion of the path of totality. Indeed the maximum duration of totality we could experience from our aircraft (at 22h 49.2m U.T.) is only 0.6 seconds longer than we will experience (at 22h 44m U.T.). To reach that point (and return to Melbourne) would require flying an extra an additional 650 km, or 45 minutes. We intend to hold that flight time (and fuel) in reserve, to be "used" prior to the eclipse if needed to compensate for any possible in-flight contingency or delay. If there are none, that time will be used for the Antarctic sightseeing part of the flight.
A. We will observe the eclipse at the maximum altitude which can be supported at this phase of the flight, without necessitating using any fuel margins. This will depend somewhat on the actual pre-eclipse (low-level Antarctic overflight) flight plan as well as weather en route and winds. The "baseline" plan for the eclipse observation described here is for 38,000 feet above mean sea level. However, a lower altitude (most likely 34,000 ft or higher) may be required,. This possibility is anticipated and is easily accommodated in real-time with no significant change in the duration or viewing aspect of the total eclipse.
A. Our intercept position at 22h 44m U.T. was also chosen to locate the aircraft sufficiently far inland mitigate normal coastal buffer zone (ice/sea interface) wind effects. The dominant wind pattern over the Antarctic plateau (far inland from the coastal regions) is katabatic. That is, the winds are primarily driven by a gravity gradient over the relatively isothermal ice sheet, and there is a strong tendency for the winds to have low velocity laminar flows. At our chosen latitude for the eclipse flight (-70S) the high-altitude wind pattern is very strongly circular, flowing clockwise at low velocity around the pole. We might expect winds of only 10-20 knots, though of course anomalous conditions can arise ("climate is what you expect, weather is what you get"). You can VIEW A GRAPHIC ANIMATION of the Antarctic polar jet stream and the winds over the continent for a weeks period of time centered on 23 November (for 2001).
A. Because the Moon's shadow is moving much faster than the aircraft, the change in relative speed, even with high winds, does not have a big effect on the duration of totality. For example, a headwind of 100 nautical miles per hour (much more than is expected) would reduce the duration of totality to 2m 25.8s, whereas a tailwind would increase it to 2m 44.9s.
A. The Sun will be 15.0 degrees above the astronomical horizon at mid-eclipse. At 38,000 ft, the apparent horizon is depressed by 3.4 degrees, so the Sun will appear to be 18.4 degrees above the apparent horizon (in the absence of any topographic features).
A. The eclipse intercept is planned such that the Sun will be "straight out" the port (left) side cabin windows, i.e., 90-degrees to our direction of flight. This will maximize the ease of visibility out the cabin windows.
A. Technically, yes, as the duration of totality would be maximized by flying an arc following the instantaneous velocity vector of the Moon's shadow. In practice, however, the aircraft's mid-eclipse trajectory is such that and the "loss" to the duration of totality is only about 0.1 seconds.
A. Where weather is concerned one can never be completely assured. However, at 38,000 feet the aircraft will be above 4/5th of the Earth's atmosphere, and at these polar latitudes airborne particulate are extremely low. In the absence of high cloud - which is uncommon but not impossible - the sky transparency along the line-of-site to the sun should be spectacular, and turbidity should be very low. The sky, during totality, at 38,000 feet should be quite dark. For a comparative example SEE A WIDE-ANGLE IMAGE of totality at 41,000 feet (similar altitude), and the lunar shadow/sky brightness taken from an aircraft window of the 20 June 1992 total solar eclipse over the South Atlantic. High-altitude particulate, which cause light-scattering from the illuminated regions outside of the shadow, over the Antarctic interior are significantly more sparse than at lower latitudes.
A. By design, the eclipse observation is planned after the Antarctic sightseeing portion of the flight. If weather conditions dictate an intercept later in U.T. (further inland), or (though much less likely) earlier in time, i.e., over the Ocean, that can be accommodated within the planned flight margins.
A. We remain highly flexible. The eclipse-observation portion of the flight is nominally planned to be conducted after about two and a half hours of low-altitude sightseeing along the Antarctic coast. That time can be used in contingency. If we are delayed we can observe the eclipse first and the sightseeing portion of the flight can be carried out after totality.
A. The flight pre-planning, including baseline and contingency (alternate) scenarios have been carried out using a highly specialized software package called EFLIGHT which symbiotically synthesizes dynamical ephemerides generation for the eclipse from a moving platform with aircraft navigation information. EFLIGHT (which is fully described HERE) was designed for in situ on the aircraft flight deck and real-time airborne eclipse navigation. It will be used in this manner on the Croydon/QANTAS flight to "guide" the aircraft to an optimal "totality run" and eclipse intercept.
A. At this time, a second Antarctic eclipse flight is planned, using an Airbus A340 operated by Lan Chile.
A. The QANTAS/CROYDON and LanChile/Sky&Telecope flight plans, shown graphically, and tabulated in detail, were co-operatively and contemporaneously designed for non-interference, and the two aircraft will not be operating in the same airspace. On a personal note, I have been privileged to have worked on (and continue to work on) the definition and planning of both flights, and and level of co-ordination between the two flights, to assure their mutual success, has been very high.
A. We have made no special plans, nor levied any requirements on the flight profile for viewing first contact or most of the ingress phase of the partial eclipse, as this nominally will occur during the "sightseeing" phase of the flight. The orientation of the aircraft, as it maneuvers for viewing along the Antarctic coastline, will likely allow some serendipitous viewing of ingress. About a half an hour before totality (the exact time dependent upon the position of the aircraft) we will break off the site-seeing portion of the flight and head to a pre-determined "hold" point just ahead of the start of the planned flight path for the "totality run". At 15 minutes before mid-eclipse (appx 13m 40s before Contact II) we will complete a heading alignment maneuver to put the aircraft on a nearly "straight line" course for a mid-eclipse intercept with the center of the umbral cone at 22h 44m. During the run up to totality the Sun will be essentially perpendicular to the direction of flight, "straight out" the left side cabin windows. This will provide an opportunity to view (and prepare photographic equipment during) the latest stages of the partial ingress phase of the eclipse, including the approach of the umbral shadow and the onset of second contact. After third contact the aircraft will continue on the totality run track for an additional approximately 4 minutes to view the first stages of the partial egress phase of the eclipse and the recession of the lunar shadow.
A. Send email to: Glenn Schneider (open email window to: gschneider@mac.com)
