This artist's concept shows the newfound Neptune-sized planet - one of the smallest extrasolar planets detected to date - circling the star 55 Cancri. The planet joins three others in orbit around 55 Cancri to form the first known four-planet system. It is the innermost of the bunch, whipping around the star every 2.8 days at just a fraction of the distance between the Sun and Earth, or 5.6 million kilometers (3.5 million miles).
In this illustration, the new planet is depicted as having a rocky composition, like Earth or Mars. In reality, astronomers do not know if the planet is rocky, or gaseous like Jupiter. Being so close to its parent star, the planet's temperature is at least a scorching 1500 Celsius (2700 Fahrenheit).
The star 55 Cancri is about 5 billion years old, a bit lighter in weight than the Sun, and is located 41 light-years away in the constellation Cancer.
Data from the Hobby-Eberly Telescope at McDonald Observatory in West Texas, the Lick Observatory in Northern California and NASA's Hubble Space Telescope were used to find the new planet using the radial velocity technique.