47 Ursae Majoris

47 Ursae Majoris

47 UMa system compared with Jupiter's orbit around the Sun. Credit: Kirk Woellert, National Science Foundation.

47 Ursae Majoris is one of the first Sun-like stars to be found to have a planet.1 This companion, 47 UMa b, was the first planet found orbiting another star that resembles Jupiter in both its mass and orbit. Its location around its central star is approximately the same as that of the asteroid belt in the Solar System. The discovery of a second planet in the 47 Ursae Majoris system, 47 UMa c, was announced in 2002 and subsequently confirmed by other groups.2


Calling 47 UMa

47 Ursae Majoris has been the target of three METI (Message to Extraterrestrial Intelligence) signals. The first, called the Teen Age Message, was sent by the 70-m Eupatoria Planetary Radar on September 3, 2001, and will reach at the star in July 2047. The second message, known as Cosmic Call 2, was sent by the same instrument on July 6, 2003, and will arrive in May 2049. Finally, 47 UMa was also the target of the first interstellar commercial when an advertisement for Doritos tortilla chips was beamed toward it by a radar array at the EISCAT European space station on the Norwegian island of Svalbard on June 12, 2008.


Central star
distance 45.9 light-years (14.1 pc)
spectral type G1V
surface temperature 5,470ºC
luminosity (Sun = 1) 1.54
mass (Sun = 1) 1.03
apparent magnitude 5.03
position RA 10h 59m 28.0s,
Dec +40° 25' 48.9"
other designations Gl 407, HR 4277, BD +41º2147, HD 95128, LTT 12934, GCTP 2556.00, SAO 43557, FK5 1282, GC 15087, HIP 53721

  b c
mass (Jupiter = 1) 2.60 ± 0.13 . 0.46
semimajor axis 2.13 AU (317 million km, 198 million mi) 3.39 AU (509 million km, 318 million mi)
orbital period 1,083 days (2.96 years) 2,190 days (6.00 years)
eccentricity 0.049 < 0.220
discovery 1996, Butler and Marcy 2002, Fischer, Marcy, et al
method of discovery radial velocity radial velocity


1. Butler, P., and Marcy, G. "A Planet Orbiting 47 UMa," Astrophysical Journal Letters, 464, L153 (1996).
2. Fischer, D. A., Marcy, G. W., Butler, R. P., Laughlin, G., and Vogt, S. S. "A Second Planet Orbiting 47 Ursae Majoris," ApJ, 564 1028 (2002).