It’s time to celebrate the moon’s importance in astronomy. This Saturday (Oct. 28), institutions worldwide will take part in International Observe the Moon Night, when they will discuss the importance of the moon in everything from eclipses to tides to astronomical observations.
The most important part of the night is simply the act of observing, particularly if you’ve never looked at the night sky or used a telescope before, said Noah Petro, the deputy project scientist for NASA’s Lunar Reconnaissance Orbiter (LRO). Petro will be at an event hosted by NASA at the Goddard Space Flight Center in Maryland.
“We have a number of opportunities for people to see what’s up in the night sky,” he said in an interview. “It’s very exciting, especially if somebody doesn’t do it normally.” NASA’s Goddard event will also include opportunities to meet scientists, as well as several activities, exhibits and visualizations. [The Moon: 10 Surprising Lunar Facts]
Petro added that, in addition to the NASA Goddard event, there are dozens of other moon-related happenings taking place worldwide. A full list is available on the International Observe the Moon website.
Many of this year’s events will focus on the role of the moon in solar and lunar eclipses. A solar eclipse happens when the moon passes in between Earth and the sun, as seen from Earth; a lunar eclipse occurs when Earth passes in between the sun and the moon.
Millions of spectators across the United States saw a spectacular total solar eclipse on Aug. 21. A total lunar eclipse will be visible on Jan. 31, 2018, in parts of the United States, northeastern Europe, Russia, Asia, the Indian Ocean, the Pacific and Australia, according to Timeanddate.com.
How to observe the moon
The moon is so large and bright in our night sky that you can look at it with no equipment at all. On Oct. 28, it will be just past the first-quarter phase and will appear half-illuminated in the sky. You’ll be able to see the moon clearly after sunset. It will set early in the morning, allowing kids to get a great view of the moon before bedtime.
With binoculars or a small telescope, you can explore the craters and other features on the right-hand side of the moon (which may appear upside down in some telescopes). You will see “maria” (dark plains), deep craters and rays of material ejected from ancient asteroid collisions. Our How to Observe the Moon infographic guide includes some key features to look for.
You can also download a free map of the moon from NASA here, which labels the craters and other features that will be visible on the lunar surface Saturday.
Experienced skywatchers recommend that you look along the terminator, or the line between day and night. This is where shadows really show off craters and cast light onto mountain ranges. Feel free to make some sketches or take digital pictures using our How to Photograph the Moon guide here.
What else to see in the night sky
Because the moon is only half-full, you will still get a good view of other objects in the night sky. Below are some of the prominent objects visible in the Northern Hemisphere on Saturday, Oct. 28.
With a small telescope or binoculars, you can see asteroid 7 Iris in the constellation Aries, though it won’t be visible to the unaided eye. According to a NASA skywatching guide, you should be able to spot this magnitude-6.9 asteroid with the proper equipment even from cities, weather permitting. The constellation Aries is in the northern part of the sky, between Pisces to its west and Taurus to its east.
Uranus is at its brightest right now; it reached opposition on Oct. 19. But it’s still hard to see it with the naked eye, so a telescope or binoculars might be necessary. Its blue glow is visible in the constellation Pisces, just to the east of Piscium (Omicron Piscium) in a “V” shape. You can see a map of Uranus’ location at NakedEyePlanets.com.
Saturn will shine in the southwest sky as night falls, not too far above the ruddy star Antares (which looks a little like Mars), according to EarthSky. Saturn’s famous rings are visible only in a small telescope, but you can spot the planet with your naked eye if you know where to look. [The Brightest Planets Visible in October 2017]
Mercury is difficult to spot just as the sun is setting, and it will likely be lost in the glare of twilight. Observers will have better luck looking at this faint planet later in November. The other visible naked-eye planet, Jupiter, is likely too close to the sun to be visible.
Early Saturday morning, after the moon has set and just before the sun rises, you will be able to see Venus and Mars in the eastern sky with your naked eye. (In binoculars, Venus and Mars look a little brighter; a large telescope may show some prominent features on Mars, but Venus is completely surrounded by clouds, and its features are invisible.)
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Although humanity has observed the moon ever since we knew to look at the night sky millennia ago, our understanding of Earth’s close neighbor continues to evolve. NASA’s Lunar Reconnaissance Orbiter has spent about eight years orbiting the moon, taking pictures of its surface and analyzing its features. Maps using LRO data are freely available online, allowing amateur astronomers to get a very-high-resolution look at the surface.
Petro said one of LRO’s current focuses is to look at surface change. Because the spacecraft has been at the moon so long, it sometimes spots craters that were created after the spacecraft arrived.
“From that, we can better identify the rate at which the surface is changing,” Petro said. “First, we’ve been able to do that on the moon, but we can take that understanding for the moon and apply that elsewhere in the solar system.” Craters are common on objects such as Mercury, asteroids, “airless” moons (moons without appreciable atmospheres) and even Mars, which has a thin atmosphere that blocks some meteors from reaching the surface.
LRO is also tracking the position of volatiles — light elements — on the moon’s surface, including hydrogen. Hydrogen is considered a strong indicator of water ice. Petro said the team is interested in learning how volatiles vary over time, and they hope LRO can reveal more information about that.
NASA last sent humans to the moon between 1969 and 1972, during the Apollo lunar landing missions. The agency is discussing a Deep Space Gateway space station that could operate near the moon, as a launching point for Mars missions. Petro said LRO is also scouting landing sites on the surface for future robotic and crewed missions.
Editor’s note: If you snap a great photo of the moon or any other night sky sight you’d like to share with Space.com and our news partners for a story or image gallery, send images and comments in to: [email protected].