The Spitzer Space Telescope measured the planet temperature , and found that the difference between the two sides of Upsilon Andromedae b of about 1 @,@ 400 degrees Celsius , ranging from minus 20 to 230 degrees to about 1 @,@ 400 to 1 @,@ 650 degrees Celsius . The temperature difference has led to speculation that Upsilon Andromedae b is tidal locked with the same side always facing Upsilon Andromedae A.