Last Quarter

Last Quarter (sometimes called Third Quarter) is the precise mirror of First Quarter: exactly half the disc is lit, but now it's the opposite half, and the Moon is three-quarters of the way through its cycle by time and orbital position rather than one-quarter. It sits roughly a week before the next New Moon.

Because of where it sits in the cycle, Last Quarter rises around midnight and is highest in the sky around dawn, then remains visible well into the morning daylight hours — making it one of the few lunar phases regularly visible in a blue daytime sky for anyone who happens to look up in the late morning.

As with First Quarter, the terminator running straight down the middle of the disc makes Last Quarter another genuinely excellent phase for telescope or binocular observing, with long shadows revealing crater walls and mountain relief that a Full Moon's flat lighting washes out — it's simply less popular to observe than First Quarter purely because it requires being up before dawn rather than out in the evening.

Last Quarter marks the last clearly-named milestone before the cycle winds down through Waning Crescent and back to New Moon, completing the roughly 29.53-day synodic month before the whole eight-phase sequence begins again.

Because Last Quarter and First Quarter show mirrored terminator lighting on opposite lunar hemispheres, comparing photographs of the same crater under each phase is a genuinely useful way to see how dramatically shadow angle changes a feature's visual appearance — a crater that looks like a subtle dimple at Full Moon can look like a deep, dramatic pit under either quarter phase's raking light.

Because Last Quarter's 90-degree phase angle is a precise, repeatable astronomical milestone rather than a fuzzy range, it can be calculated to the minute using the same orbital mechanics this site's tools apply elsewhere — distinct from the broader angular windows the four gibbous and crescent phases cover.

This phase is sometimes called Third Quarter in older astronomy texts and some non-English traditions, a naming variation worth knowing since both terms describe exactly the same phase and neither is more technically correct than the other — purely a matter of which counting convention a given source follows.

This phase's pre-dawn timing means it often gets less attention from casual observers than First Quarter, even though the actual surface detail on view is just as dramatic — purely a matter of convenience rather than any real difference in what's visible.

A star chart or phone astronomy app can help identify exactly which crater or feature you're looking at along the terminator during this phase, turning a casual glance into a genuinely rewarding identification session.

A quiet, dark backyard is often all the setup this phase genuinely requires — no need for a remote dark-sky site to get real value from watching it.

A comfortable chair and a warm drink can make the difference between a rushed five-minute glance and a genuinely satisfying half-hour session watching this phase climb toward dawn.

Even five minutes of quiet observation before heading back inside is enough to genuinely appreciate this phase's terminator detail.