But the advice is mixed for summer flights. âI would suggest buying your airfares for summer as soon as you can,â said Krista Pappas, global travel industry director for Bing, citing high fuel prices, tight seating capacity and strong consumer demand as a recipe for rising rates.
A sidereal period is also defined as the position of an object with respect to the stars. The synodic month is a bit longer than the sidereal month. When a synodic month lasts 29 days, 12 hours, and 44 minutes, a sidereal month lasts 27 days, 7 hours, and 43 minutes.
This is known as a sidereal month and is measured by  observing how long it takes the Moon to pass a fixed star on the  celestial sphere.  A synodic month is 29.53 days (29 days, 12  hours, 44 minutes, 2.8 seconds) and is measured from New Moon to  New Moon.