Extra Solar Planets
Note that recent observations have slightly altered some of the parameters of the star and its planets. 55 Cancri, or more properly Rho Cancri, is a binary star about 42.4 light-years away from Earth. The primary star, 55 Cancri A, is a yellow dwarf type G8V star with a smaller red dwarf companion, 55 Cancri B. The two are more than 1,000 AUs (150 billion km or more than 93 billion miles) apart. 55 Cancri A is very slightly larger (1.15 solar radii) and heavier (1.03 solar masses) than the Sun, and about 5½ billion years old. At present, it has five confirmed planets, none of which is truly Earth-sized. 55 Cancri B is a much smaller (30% of the Sun's diameter and 13% of its weight) type M4V dwarf.
The Visualization, in the introduction, includes this system as its only Five Planet System.
The Visualization, in the introduction, includes this system as its only Five Planet System.
55 Cancri
| Planet | Description (in order from the star; all quoted values are approximate) |
| 55 Cancri e | This planet is believed to be about 8.5 times heavier than the Earth, although it could be at least 25% larger than this minimum. It is the smallest planet in the system, being about 1.63 times the diameter of the Earth. It orbits at only about 2.3 million km (1.45 million miles) from the star, taking about 17 hours and 41 minutes for each orbit. Previously, the radius of the orbit was thought to be about 5.65 million km. |
| 55 Cancri b | This planet is nearly as big as Jupiter (c. 82½% Jupiter's mass) and about 262 times heavier than the Earth! It is about 17.2 million km (10.7 million miles) from 55 Cancri A , which it takes about 14 days 16 hours to orbit. |
| 55 Cancri c | This planet is about 17% of Jupiter's mass, which is about 54 times heavier than the Earth! It is about 36 million km (22.3 million miles) from 55 Cancri A , which it takes about 44 days 8 hours to orbit. |
| 55 Cancri f | This planet is about 15½% of Jupiter's mass, which is about 49 times heavier than the Earth! It is about 117 million km (73 million miles) from 55 Cancri A , which it takes about 260 days to orbit. |
| 55 Cancri d | This planet is enormous at about 3.82 times Jupiter's mass! It is about 5.74 AU (860 million km or 534 million miles) from 55 Cancri A , which is a little further than the Sun Jupiter separation of c. 5.2 AU. It takes more than 14 Earth years for one orbit, where Jupiter takes about 11.9 years. |