L1 The Moon
Number one on the list isn't a crater or a dome — it's the whole disk itself. Charles Wood built the Lunar 100 as a ladder of difficulty, and the very first rung is simply looking up.
📝 Observation Log — L1 The Moon
0/6 CompleteWhen to Observe The Moon
L1 is the only entry on the list with no bad night. Every phase shows something different — a thin crescent puts the terminator's low-angle relief on full display, while a Full Moon washes out shadows but lights up ray systems and albedo contrasts that vanish under oblique lighting. There's no wrong time to start the list; there's only a different lesson depending on when you look.
- No Equipment Required: Every feature on this entry is visible to the naked eye, from city balconies to dark-sky sites alike — the Moon is bright enough to see through nearly any light pollution or thin cloud that would erase a deep-sky object entirely.
- Watch the Terminator Move: Because the Moon rotates once for every orbit, the same features cross from sunrise to sunset over about two weeks — return to the same target on consecutive nights and watch the lighting transform it.
- Track Libration Over Months: The Moon's slight wobble in its orbit means slightly more than half its surface becomes visible from Earth over time — a slow, ongoing bonus that rewards observers who keep coming back rather than treating any single night as complete.
What to Look For
Even without optical aid, the naked eye picks out the dark patches of mare basalt against the brighter highlands — the pattern popularly read as a face, a rabbit, or a woman's profile depending on the culture. This is the same light-dark dichotomy that occupies L3 on the list, visible from the very first glance.
Unlike a planet or star, the Moon's edge holds sharp and steady even in modest binoculars, since there's no atmosphere on the Moon to blur it and Earth's own air affects it far less than it does fainter, more distant targets. That crispness is itself a clue to the Moon's airless nature.
The boundary between lit and unlit hemispheres isn't a smooth arc — even naked-eye, and especially in binoculars, it visibly zigzags where tall crater rims and mountain peaks catch sunlight before the lower terrain around them.
The Science: A World Split in Two
The Moon's most fundamental scientific puzzle isn't any single feature — it's the fact that the hemisphere facing Earth and the one that never does are almost entirely different worlds.
Vital Statistics
The Moon spans about 3,474 km in diameter, roughly a quarter of Earth's, orbiting at an average distance of about 384,400 km. It's tidally locked, keeping the same hemisphere permanently facing Earth. Its L100 distinction: L1, the easiest and first entry on the list — the whole disk, visible to the naked eye on any clear night.
Two Faces, One World
Dark mare basalt covers roughly 31% of the near side but only about 1–2% of the far side, a striking asymmetry tied to crustal thickness — GRAIL gravity data shows the far side's crust runs on average around 20 km thicker than the near side's, making it far harder for magma to reach the surface there. The cause of that thickness difference remains an active area of research, with hypotheses ranging from a slow-accreting companion moon to asymmetric heating during the crust's early formation.
Born From a Giant Impact
The leading model holds that the Moon formed roughly 4.5 billion years ago when a Mars-sized body collided with the young Earth, throwing debris into orbit that coalesced into the Moon. In its earliest history the Moon is thought to have been covered by a global magma ocean; as it cooled, lighter plagioclase crystals floated upward to form the bright anorthosite crust that makes up today's highlands, while the mare basalts filling low-lying basins came later, mostly between about 3.8 and 3.1 billion years ago.
Every other entry on the Lunar 100 is a detail within this larger picture. L1 is the whole canvas — and the fact that it's this easy to see, yet still this actively studied, is exactly why Charles Wood put it first.
Return to the List
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Frequently Asked Questions
The questions people bring to L1 most often — mostly about timing, distance, and what's happening with the Moon right now.
When is the next full moon?
Full moons occur roughly every 29.5 days, the length of the Moon's synodic month. Rather than a fixed date, the exact day shifts slightly each cycle. The live tracker at the top of this page shows the next confirmed Full Moon date, updated automatically as the month progresses.
Is it a full moon tonight?
Only for a brief window — technically, "full" refers to the exact moment the Moon sits opposite the Sun, not an entire night. It looks essentially full to the naked eye for two to three nights around that moment. Check today's phase and illumination percentage in the live tracker above for the current status.
When was the last full moon?
Since full moons repeat on a roughly 29.5-day cycle, the last one fell about a month before the next date shown in the live tracker above. Subtract roughly 29.5 days from the upcoming Full Moon date for an approximate answer, or check a Moon phase calendar for the exact day.
When is the next new moon?
New Moon — when the Moon sits between Earth and the Sun and its near side goes dark — also follows the same ~29.5-day cycle, roughly two weeks offset from Full Moon. The live tracker above lists the next confirmed New Moon date alongside the next Full Moon.
When is the next blood moon?
A "blood moon" is a total lunar eclipse — the Moon passes fully into Earth's shadow and takes on a reddish color from sunlight filtering through Earth's atmosphere. These are far less frequent than ordinary full moons, since they require a precise alignment. The Upcoming Eclipses section of the live tracker above lists the next confirmed lunar and solar eclipse dates.
How far is the Moon from Earth?
The Moon orbits at an average distance of about 384,400 km (238,900 miles) from Earth, but that distance actually varies by tens of thousands of kilometers because the orbit is elliptical, not circular — closer at perigee, farther at apogee. The live tracker above shows today's actual distance, recalculated continuously.
How long does it take to get to the Moon?
It depends heavily on the mission profile. The Apollo missions took about three days using a direct trajectory built for speed. Uncrewed missions using fuel-efficient low-energy transfers can take weeks or even months to arrive, trading travel time for a much smaller fuel budget.
Why is the Moon orange tonight?
An orange or reddish Moon near the horizon is almost always an atmospheric effect, not a change in the Moon itself. When the Moon is low in the sky, its light passes through much more atmosphere than when it's overhead, scattering away shorter blue wavelengths and letting warmer orange and red tones through — the same reason sunsets turn orange. Smoke, haze, and dust in the air can intensify the effect.