Data Analysis problem set
AdvancedIOAA 2016 | Bhubaneswar, India | Data Analysis D2 | 50 pt

2016 D2 | The Moon's size, orbit and the distance to the Sun

Geocentric ephemerides of the Moon for September 2015 are given in the table. Each reading was taken at 00:00 UT. Assume the observer is at the centre of the Earth, and "angular size" means the angular diameter of the object or shadow. A total lunar eclipse occurred this month.

(D2.1) In September 2015, apogee of the lunar orbit is closest to New Moon / First Quarter / Full Moon / Third Quarter. (3)

(D2.2) In September 2015, the ascending node of the lunar orbit on the ecliptic is closest to New Moon / First Quarter / Full Moon / Third Quarter. (4)

(D2.3) Estimate the eccentricity ee of the lunar orbit from the data. (4)

(D2.4) In the paper, a composite image of the eclipse shows the Moon at several times. A geometric construction (find the centre of the umbra from chords through the shadow edges) gives the umbra's diameter. Take the result: θumbra≈2.76 θMoon\theta_{\rm umbra} \approx 2.76\,\theta_{\rm Moon}. (8)

(D2.5) The Sun subtends θSun=1915.0′′\theta_{\rm Sun} = 1915.0'' at Earth on the day of the eclipse. Rays from diametrically opposite edges of the solar disc graze the Earth. Calculate the angular size of the penumbra θpenumbra\theta_{\rm penumbra} in terms of θMoon\theta_{\rm Moon}. (9)

(D2.6) Let θEarth\theta_{\rm Earth} be the angular size of the Earth seen from the centre of the Moon. Express θMoon\theta_{\rm Moon} (seen from the Earth's centre on the eclipse day) in terms of θEarth\theta_{\rm Earth}. (5)

(D2.7) Estimate the radius of the Moon RMoonR_{\rm Moon} in km. (3)

(D2.8) Estimate the perigee and apogee distances of the Moon. (4)

(D2.9) Use the data for 10 September to estimate the distance to the Sun. (10)

Use R⊕=6371R_\oplus = 6371 km.

Geocentric ephemeris of the Moon, September 2015, 00:00 UT
DateR.A. (h m s)Dec. (° ′ ″)Angular size (″)PhaseElongation
Sep 010 36 46.02+3 06 16.81991.20.927148.6° W
Sep 021 33 51.34+7 32 26.11974.00.852134.7° W
Sep 032 30 45.03+11 25 31.11950.70.759121.1° W
Sep 043 27 28.48+14 32 04.31923.90.655107.9° W
Sep 054 23 52.28+16 43 18.21896.30.54695.2° W
Sep 065 19 37.25+17 55 04.41869.80.43882.8° W
Sep 076 14 19.23+18 07 26.61845.50.33670.7° W
Sep 087 07 35.58+17 23 55.61824.30.24359.0° W
Sep 097 59 11.04+15 50 33.01806.50.16347.5° W
Sep 108 49 00.93+13 34 55.61792.00.09736.2° W
Sep 119 37 11.42+10 45 27.71780.60.04725.1° W
Sep 1210 23 57.77+7 30 47.71772.20.01514.1° W
Sep 1311 09 41.86+3 59 28.81766.50.0013.3° W
Sep 1411 54 49.80+0 19 50.21763.70.0057.8° E
Sep 1512 39 50.01−3 20 03.71763.80.02618.6° E
Sep 1613 25 11.64−6 52 18.81767.00.06529.5° E
Sep 1714 11 23.13−10 09 04.41773.80.12040.4° E
Sep 1814 58 50.47−13 02 24.71784.60.18951.4° E
Sep 1915 47 54.94−15 24 14.61799.60.27062.5° E
Sep 2016 38 50.31−17 06 22.81819.10.36373.9° E
Sep 2117 31 40.04−18 00 52.31843.00.46385.6° E
Sep 2218 26 15.63−18 00 41.71870.60.56797.6° E
Sep 2319 22 17.51−17 00 50.61900.90.672110.0° E
Sep 2420 19 19.45−14 59 38.01931.90.772122.8° E
Sep 2521 16 55.43−11 59 59.61961.10.861136.2° E
Sep 2622 14 46.33−8 10 18.31985.50.933150.0° E
Sep 2723 12 43.63−3 44 28.72002.00.981164.0° E
Sep 280 10 48.32+0 58 58.22008.31.000178.3° E
Sep 291 09 05.89+5 38 54.32003.60.988167.4° W
Sep 302 07 39.02+9 54 16.11988.40.947153.2° W

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