After this study was published, more scientists started to look for other planets that orbit Gliese 581. In the 2007, another group of astronomers said that they found two more planets. These two planets were named 581c and 581d. For planet c, the scientists measured a mass of 5.06 times the Earth's mass. They found that the planet's orbit lasts for 12.931 days. For planet d, they found a mass of 8.3 times the Earth's mass, and an orbit time of 83.4 days.