The planet program shows the positions of the planets and some other information about them, at any location and time.
The program was mainly written by others, as stated in comments near the start of planet.c. I added several enhancements, such as additional columns in the output.
The planet program has these options:
Usage: planet [-t H:M:S] [-d m/d/y] [-z tz] [-a DoM'S"] [-o DoM'S"]
where
t = time (H:M:S [H=hours, M=mins, S=secs] 24-hour clock, default=now)
d = date (month/day/year, must supply all digits of year, default=today)
z = timezone number (count west from Greenwich, default=central)
a = latitude (DoM'S" [D=degrees, M=mins, S=secs] north, default=42o2')
o = longitude (DoM'S" [D=degrees, M=mins, S=secs] west, default=88o16')
In time, latitude, and longitude, the seconds may be omitted, or minutes and
seconds may be omitted. Also, the symbol after the last number (o'":) may
be omitted. Use negative latitude for south, negative longitude for east.
All of the options are optional, defaulting as stated above. Don't type the
[brackets]; they are just there to emphasize that each option is optional.
Example:
planet -d 9/26/2014 -t 21:30
and it tells you
planet.c Version 1.10 Date: September 26, 2014 Time: 21:30:00 (CDT) Julian date: 2456927.604167 Place: 42o 2' 0" north latitude, 88o 16' 0" west longitude OBJECT R.A. DEC DIST WIDTH ELONG ILLUM HOUR ANG ALTITUDE AZIMUTH Sun 12h 14m 23s - 1o 33' 1.002 1913.3" 0o 0' ---- 8h 45m 47s -30o 39' 299o 26' Mer 13h 44m 47s -14o 20' 0.891 7.6" 25o 44' 49% 7h 15m 24s -23o 28' 271o 37' Ven 11h 49m 40s + 2o 41' 1.701 9.8" 7o 30' 99% 9h 10m 31s -31o 7' 308o 9' Mar 16h 28m 6s -23o 16' 1.514 6.2" 65o 4' 88% 4h 32m 5s - 0o 31' 238o 26' Jup 9h 11m 28s +16o 46' 5.897 33.4" 48o 41' 99% 11h 48m 42s -31o 9' 356o 50' Sat 15h 12m 58s -15o 50' 10.605 15.7" 46o 15' 100% 5h 47m 13s - 8o 13' 256o 3' Ura 0h 56m 6s + 5o 14' 19.033 3.7" 168o 57' 100% 20h 4m 5s +26o 15' 107o 55' Nep 22h 30m 9s -10o 13' 29.087 2.3" 151o 31' 100% 22h 30m 2s +33o 49' 153o 3'DIST is the distance from earth, in astronomical units. WIDTH is in arcseconds, as viewed from earth. ILLUM is the percentage of its disk that is illuminated by the sun, as seen from earth.
In Windows, the default width of the command window is 80 characters, but the output of planet is wider than that, so that doesn't look good. You can't pull on the boundary of this window to widen it. You need to right click its top bar, choose "properties", click "layout", and then set screen buffer width and window size width to some bigger number, say, 100.