User Guide

A NEW SUN
APPENDIX 5
227
Eurytion EarthE/Earth RatioMercuryE/Merc Ratio
Mass (kg) 5.16 x 10
23
5.98 x 10
24
0.09 3.23 x 10
23
1.60
Equat. radius (km) 2820 6380 0.44 2439 1.16
Dist. from star (km) 7.06 x 10
10
1.50 x 10
11
0.47 5.79 x 10
10
1.22
Surface area (km
2
) 9.98 x 10
7
5.10 x 10
8
0.20 7.47 x 10
7
1.34
Standard gravity (m/s
2
) 4.33 9.81 0.44 3.63 1.19
Escape velocity (m/s) 4940 11,200 0.44 4300 1.15
Density (kg/m
3
) 5503 5519 1.00 5420 1.02
Size of sun (angular degrees) 0.62 0.27 2.31 0.70
0.89
Year (Earth days) 113.8 365.3 0.31 88.0 1.29
Surf. temperature (°K) 438 288 ñ 452 ñ
Surf. temperature (°C) 165 15 ñ 179 ñ
Solar constant (W/m
2
) 8999 1383 6.51
SUGGESTED READING
NONFICTION
ALPHA CENTAURI, THE NEAREST STAR Isaac Asimov
Lothrop, Lee & Shepard Company, a Division of William Morrow & Comany,
Inc., New York, 1976
Published in 1976, by William Morrow & Company (New York), this book is a
bit dated but still contains a solid explanation of how we determined Alpha
Centauri is the nearest star, plus additional details on the nature and structure
of this trinary star system. You’ll have a hard time finding it in a bookstore;
you might have better luck with the juvenile section of your nearest library.
WWW.NASA.GOV
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