Some nights when we look up at the moon, it is full and bright; sometimes it is just a sliver of silvery light. These changes in appearance are the phases of the moon. As the moon orbits Earth, it cycles through eight distinct phases. The four primary phases occur about a week apart.
Lunar calendar for 2018
Here are the dates of the moon’s phases for 2018, according to NASA. Times and dates are in Eastern U.S. time.
| 1st Qtr | Full Moon | Last Qtr | New Moon | ||||
| Jan 1 | 21:24 | Jan 8 | 17:25 | Jan 16 | 21:17 | ||
| Jan 24 | 17:20 | Jan 31 | 08:27 | Feb 7 | 10:54 | Feb 15 | 16:05 |
| Feb 23 | 03:09 | Mar 1 | 19:51 | Mar 9 | 06:20 | Mar 17 | 09:12 |
| Mar 24 | 11:35 | Mar 31 | 08:37 | Apr 8 | 03:18 | Apr 15 | 21:57 |
| Apr 22 | 13:49 | Apr 29 | 20:58 | May 7 | 22:09 | May 15 | 07:48 |
| May 21 | 23:49 | May 29 | 10:20 | Jun 6 | 14:32 | Jun 13 | 15:43 |
| Jun 20 | 06:51 | Jun 28 | 00:53 | Jul 6 | 03:51 | Jul 12 | 22:48 |
| Jul 19 | 15:52 | Jul 27 | 16:21 | Aug 4 | 14:18 | Aug 11 | 05:58 |
| Aug 18 | 03:49 | Aug 26 | 07:56 | Sep 2 | 22:37 | Sep 9 | 14:01 |
| Sep 16 | 19:15 | Sep 24 | 22:53 | Oct 2 | 05:45 | Oct 8 | 23:47 |
| Oct 16 | 14:02 | Oct 24 | 12:45 | Oct 31 | 11:40 | Nov 7 | 11:02 |
| Nov 15 | 09:54 | Nov 23 | 00:39 | Nov 29 | 19:19 | Dec 7 | 02:20 |
| Dec 15 | 06:20 | Dec 22 | 12:49 | Dec 29 | 04:34 | ||
Phases of the moon
The moon, like Earth, is a sphere, and it is always half-illuminated by the sun. However, as the moon travels around Earth, we see more or less of the illuminated half. The moon’s phases describe how much of the moon’s disk is illuminated from our perspective.
New moon: The moon is between Earth and the sun, and the side of the moon facing toward us receives no direct sunlight; it is lit only by dim sunlight reflected from Earth.
Waxing crescent: As the moon moves around Earth, the side we can see gradually becomes more illuminated by direct sunlight.
First quarter: The moon is 90 degrees away from the sun in the sky and is half-illuminated from our point of view. We call it “first quarter” because the moon has traveled about a quarter of the way around Earth since the new moon.
See the full infographic
. ” data-options-closecontrol=”true” data-options-fullsize=”true”/>Credit: Karl Tate, SPACE.com
Waxing gibbous: The area of illumination continues to increase. More than half of the moon’s face appears to be getting sunlight.
Full moon: The moon is 180 degrees away from the sun and is as close as it can be to being fully illuminated by the sun from our perspective. The sun, Earth and the moon are aligned, but because the moon’s orbit is not exactly in the same plane as Earth’s orbit around the sun, they rarely form a perfect line. When they do, we have a lunar eclipse as Earth’s shadow crosses the moon’s face.
Waning gibbous: More than half of the moon’s face appears to be getting sunlight, but the amount is decreasing.
Last quarter: The moon has moved another quarter of the way around Earth, to the third quarter position. The sun’s light is now shining on the other half of the visible face of the moon.
Waning crescent: Less than half of the moon’s face appears to be getting sunlight, and the amount is decreasing.
Finally, the moon is back to its new moon starting position. Now, the moon is between Earth and the sun. Usually the moon passes above or below the sun from our vantage point, but occasionally it passes right in front of the sun, and we get a solar eclipse . [Infographic: How Moon Phases Work ]
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