Many stargazers enjoy the challenge of spotting the moon in the evening twilight sky as soon as possible after its dark new moon phase. But this month, moon lovers should rise at dawn instead, and search for the "old moon" just before it passes into the sun's glare and is not visible at all.
August is not a good month to hunt for the moon just after its new moon phase. Just after the sun sets, the ecliptic is at a very shallow angle to the horizon, so the moon is very low. This makes the moon very hard to spot in the glow of twilight. During new moon, the moon is at a point in its orbit where it is between the Earth and the sun. Because of the mechanics of the moon, at this time it usually rises and sets with the sun. [More: How Moon Phases Work]
This graphic shows where to look to spot the moon before it hits new moon at 11:09 p.m. Eastern Daylight Time on Monday, Aug. 9.
The only time you can see the moon exactly at new moon is on the rare occasions when there is a solar eclipse, and the moon is visible ? with no detail ? as a dark object blocking the sun. But because the moon's orbit is tilted slightly with respect to the orbit of Earth around the sun, this only happens when the paths come into certain alignment. The most recent total solar eclipse occurred on July 11.
At other new moons, the moon passes above or below the sun, and it is hidden from our view by the overwhelming glare of the sun.
The morning before the date of new moon, Sunday Aug. 8, it should be possible to catch a last glimpse of the "old moon" in the pre-dawn sky. The slender crescent moon will rise a little after 4 a.m. local time, about two hours before sunrise at 6 a.m. The exact times will vary depending on where you are located in your time zone.
Observing the eastern sky just before dawn also gives you the jump on the season. The slim crescent moon will be surrounded by the brilliant stars of winter, a full six months before they come to dominate our winter evening sky. This is because of the rotation of the Earth and its orbital motion around the sun.
Just above and to the left of the moon are the famous twins, Castor and Pollux, in the constellation Gemini. To the right of the moon is Orion with its pair of first magnitude stars, red Betelgeuse and white Rigel, along with Orion's Belt and Sword. Higher in the sky will be brilliant Capella in Auriga and glowing red Aldebaran in Taurus. The latter is surrounded by the Hyades star cluster, while the more famous Pleiades star cluster rides higher still.
All in all, a summer treat, seeing a rare phase of the moon and the "winter" sky in warm temperatures for a change. Worth getting up early to see.
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This article was provided to SPACE.com by Starry Night Education, the leader in space science curriculum solutions.