Q1: Examine
the above picture. Identify the objects in the picture. What unusual
phenomena do you see in this picture? Describe them.
The image is of the surface of the sun through a telescope with
an Halpha filter, showing solar surface structures (prominences
and granules). An airliner is flying in front of the sun, and its
turbulent contrail is clearly visible, as well as atmospheric turbulence
about the aircraft.
Q2: The
aircraft in the picture appears to be a MD11 airliner, of known
dimensions (wingspan 51.8m, length 61.2m, height 17.7m). Given that
the sun subtends a known angle of 33 minutes of arc, can you use
the definition of arc length to determine the range to the aircraft
from the photographer?
The sun is 33 minutes in diameter, or 33 / 60 * 2p
/ 360 = 9.6 x 10^{3} radians of arc. On my printout of
this image, the aircraft measures to be 3.0 cm long and the sun
measures 17.5 cm across, so the aircraft subtends an angle of 3
/ 17* 9.6 x 10^{3} rad = 1.7 x 10^{3} rad. Assuming
a projected aircraft length of 60m, and the arc length formula s
= rq; r = s / q = 60 m / 1.7 x 10^{3} rad. = 35 km slant
angle to the aircraft. The aircraft is 35 km away from the observer.
Q3: Given
a sunearth distance of approximately 150 x 10^{6} km, can
you determine the approximate height of the solar prominence pictured
at about 8:30 on the edge of the sun's disk? Compare the size of
the prominence to the length of the aircraft, and to the radius
of the Earth (approximately 6,400 km).
The solar prominence measures 0.4 cm high on my printout of
the picture, so it subtends 0.4 / 15 * 9.6 x 10^{3} rad
= 2.2 x 10^{3} rad. Given r = 150 x 10^{8} km;
then s = rq = 150 x 10^{8} km * 2.2 x 10^{3} rad
= 33,000 km high. This is more than 5 Earth radii high, or half
a million MD11 lengths in height.
