The brightest Cepheid on the sky, located 1,000 light-years away, lies 8 degrees south of Altair. The changes in brightness of this giant star can be easily observed with the naked eye. Its brightness fluctuates regularly between 3.7 mag and 4.4 mag over a period of 7 days and 4 hours. It is advisable to compare the changes in its brightness with the stars θ, δ (3 mag), and λ (4 mag).