Out With the Harvest, In With the Hunt

The International Observe the Moon Night is happening Oct. 5!

In the wake of the beautiful Harvest Moon seen Sept. 14, Earth’s satellite now enters its waning phase, shrinking slice by slice into a visible semicircle as the rotating Earth spins around the Sun and its shadow is cast past us onto the Moon.

This period of waxing or waning is commonly known as a “gibbous” period, a term meaning “convex” or “rounded.” The term originated in the 15th century, though the Oxford English Dictionary suggests it was first applied to describe the Moon in 1690.

Gradually, over the coming month, the Moon will cycle toward its next full period – the Hunter’s Moon, also known as the Blood Moon or Sanguine Moon, due in mid-October. Various Native American tribes gave the Moon this name to reflect the falling leaves of autumn and the fattening of deer and other animals to prepare for the winter to come.

Speaking of coming events, the International Observe the Moon Night is happening Oct. 5! Learn more about NASA’s plans and how you can join in the fun here.

Space Station Sees Meteor over California Coast

The Expedition 59 crew on board the International Space Station captured this image of a meteor at 7:21:23 GMT on May 10, on a night pass over the Pacific Ocean and California coast. (Image courtesy of the Earth Science and Remote Sensing Unit, NASA Johnson Space Center)
The Expedition 59 crew on board the International Space Station captured this image of a meteor at 7:21:23 GMT on May 10, on a night pass over the Pacific Ocean and California coast. (Image courtesy of the Earth Science and Remote Sensing Unit, NASA Johnson Space Center)

Happy Solstice, Skywatchers

It’s the first day of summer here in the Northern Hemisphere, and the first of winter in the Southern Hemisphere. Why the difference? It’s all about Earth’s tilt!

During the solstices, Earth reaches a point where its tilt is at the greatest angle to the plane of its orbit, causing one hemisphere to receive more daylight than the other.
During the solstices, Earth reaches a point where its tilt is at the greatest angle to the plane of its orbit, causing one hemisphere to receive more daylight than the other. (NASA/Genna Duberstein)

Earth’s axis is an imaginary pole going right through the center of Earth from “top” to “bottom.” Earth spins around this pole, making one complete turn each day. That is why we have day and night, and why every part of Earth’s surface gets some of each.

Earth’s axis is always tilted 23.5˚ with respect to the Sun. Today, the north pole is tipped toward the Sun, and the south pole is tipped away from the Sun. The northern summer solstice is an instant in time when the north pole of the Earth points more directly toward the Sun than at any other time of the year.

The solstice—meaning “sun stands still” in Latin—occurs at 10:54 a.m. CDT.

Here Comes the Sun… and Moon!

Happy equinox, Earthlings! March 20 marks the spring equinox, one of two seasonal markers in Earth’s year-long orbit when the Sun appears to shine directly over the equator, and daytime and nighttime are nearly equal lengths–12 hours–everywhere on the planet.

During the equinoxes, both hemispheres receive equal amounts of daylight. (Image not to scale.)
During the equinoxes, both hemispheres receive equal amounts of daylight. (Image not to scale.) (NASA/GSFC/Genna Duberstein)

It’s the start of astronomical spring in the Northern Hemisphere, meaning more sunlight and longer days. From here until the beginning of fall, daytime will be longer than nighttime as the Sun travels a longer, higher arc across the sky each day, reaching a peak at the start of summer. It’s just the opposite in the Southern Hemisphere, where March 20 marks the fall equinox.

What’s more? The first full Moon of spring will rise tonight, lighting the skies on the equinox. Usually, a full Moon arrives a few days to weeks before or after the equinox. It’s close, but not a perfect match. Tonight’s full Moon, however, reaches maximum illumination less than four hours after the equinox. There hasn’t been a comparable coincidence since the spring equinox in 2000.

When the Moon, on its orbit around Earth, reaches the point farthest from the Sun, we see a full Moon.
When the Moon, on its orbit around Earth, reaches the point farthest from the Sun, we see a full Moon. (NASA/GSFC/Genna Duberstein)

And because the Moon is near perigee, it qualifies as a supermoon–the third and final of 2019. It’s not a big supermoon, so you won’t really be able to see the difference between this full Moon and any other one with your eyes. But keep an keep an eye on the Moon as it rises and creeps above the eastern skyline. A low-hanging Moon can appear strangely inflated. This is the Moon illusion at work.

Super or seemingly not, it’s a rare celestial coincidence to usher in springtime.

Ask an Astronomer: What’s a Supermoon?

“The second supermoon of 2019 happened Feb. 19. The third of 2019 will happen March 19. But what’s a supermoon? We asked NASA astronomer Mitzi Adams what’s really going on here. Here’s her answer!”

Like the orbits of all bodies in the solar system, the Moon’s orbit around Earth is not circular, it has an oval or elliptical shape, with Earth slightly offset from the center. As a result, there are two distance extremes of each orbit: closest approach, known as perigee, and the farthest, or apogee. When the Moon is at closest approach and within a day or so of being full, it is called a supermoon because the Moon will be at its brightest and largest.

For the supermoon on Feb.19, the Moon will be full only six hours after it reaches the perigee distance of its orbit, making it the brightest and largest full Moon of the year. A supermoon also occurred in January with a slightly more distant perigee, a mere 362 miles (583 kilometers) farther away, but 14 hours after the full Moon. However, January’s supermoon included a total lunar eclipse seen in all of North and South America. The third and last supermoon of the year will happen March 19, when the perigee distance will be reached a day and five hours before the full Moon (see the table below for details).

Date Perigee Distance Time Before or After Full Moon
Jan. 21 222,043 miles (357,344 km) 15 hours after
Feb. 19 221,681 miles (356,761 km) 6 hours before
March 19 223,308 miles (359,380 km) 1 day, 5 hours before
A total lunar eclipse accompanied the first in a trilogy of supermoons in 2019.
A total lunar eclipse accompanied the first in a trilogy of supermoons in 2019. Credit: NASA/MSFC/Joe Matus

To watch tonight’s supermoon, or any full Moon, simply look for the Moon to rise in the east as the Sun sets in the west. The Moon will look extremely large when it rises and sets. This “Moon illusion” happens when the Moon is close to the horizon and there are objects within our line of sight such as trees or buildings. Because these relatively close objects are in front of the Moon, our brain is tricked into thinking the Moon is much closer to the objects that are in our line of sight. At Moon rise or set, it only appears larger than when it is directly overhead because there are no nearby objects with which to compare it. You can check this. When the Moon rises, hold a coin at arm’s length so that the coin covers the Moon. Repeat this throughout the evening and you will see that the Moon’s size does not change.

As it rises on Feb. 19, the Moon will be in the constellation of Leo. However, since the Moon is so bright, you may have trouble seeing the bright star Regulus, which is at the end of the “backwards question mark” that makes Leo easy to spot.

Regulus
Credit: Stellarium

Looking more or less directly overhead, you could see the famous constellation Orion the Hunter with bright stars Betelgeuse, a reddish star, and Rigel, a bluish star. With a telescope or binoculars, you might be able to pick out the Orion nebula just below the belt stars of Orion, Alnitak, Alnilam, and Mintaka.

Great Nebula in Orion
Credit: Stellarium

To the west of Orion you should be able to spot reddish Mars.

Mars
Credit: Stellarium

As we observe this supermoon, keep in mind that 2019 marks the 50th anniversary of a great technological feat ­­– humans travelled to the Moon, walked on its surface and returned safely to Earth. Twelve people walked on the Moon. Neil Armstrong and Buzz Aldrin were the first two, but let us not forget the other ten: Alan Bean, Charles “Pete” Conrad, Edgar D. Mitchell, Alan Shepard, Dave Scott, James Irwin, John Young, Charles Duke, Eugene “Gene” Cernan and Harrison Schmitt. These men, along with the command module pilots Michael Collins, Dick Gordon, Stu Roosa, Al Worden, Ken Mattingly, Ron Evans and the multitudes of support staff back on Earth, fulfilled a dream of exploring our nearest neighbor in space. As NASA and its commercial and international partners plan to return the Moon over the next decade with a long-term continued presence, the list of Moon walkers will surely include women, as well.

A good resource for more information on supermoons may be found here: https://solarsystem.nasa.gov/moons/earths-moon/what-is-a-supermoon/.

Constellation screenshots are from Stellarium, a planetarium software package that is accompanied by a GNU General Public License

Mitzi Adams is a solar scientist in the Heliophysics and Planetary Science Branch at NASA’s Marshall Space Flight Center.

International Observe the Moon Night

Did you know there is a night set aside each year to observe Earth’s closest celestial neighbor, the Moon? International Observe the Moon Night has been held annually since 2010 and is a worldwide celebration of the Moon and lunar science. Each year, the celebration is held in September or October when the Moon is in the first quarter because it is visible in the afternoon and early evening hours when most events are held.International Observe the Moon Night 2018 graphic

If you live in or near Huntsville, Alabama, you can join our local celebration Saturday, Oct. 20, from 5:30-8:30 p.m. CDT at the U.S. Space & Rocket Center’s Davidson Center. The event is hosted by NASA’s Marshall Space Flight Center’s Planetary Missions Program. Members of the public are encouraged to attend and it is free. The event will include lunar and solar system exploration exhibits and a variety of hands-on activities for children and adults. Don’t live in Huntsville? No worries! There are events held worldwide and you can find a list of them here.

Full moon.As you are gearing up for your own International Observe the Moon Night celebration, check out these fun facts about the Moon.

  • The Moon is Earth’s satellite and orbits the Earth at a distance of about 384,000 km or 239,000 miles.
  • The Moon makes a complete orbit around the Earth in 27 Earth days. The Moon keeps the same side or face, towards the Earth during its orbit.
  • More than 100 spacecraft have been launched to explore the Moon. It is the only celestial body beyond Earth visited by human beings.
  • Astronauts brought back a total of 842 pounds of lunar rocks and soil to Earth.
  • The 50th anniversary of the Apollo 11 landing on the Moon will be next summer on July 20, 1969. Neil Armstrong was the first human to set foot on the Moon, followed by Buzz Aldrin.

Astronaut Edwin E. Aldrin Jr., lunar module pilot of the first lunar landing mission, poses for a photograph beside the deployed United States flag during an Apollo 11 extravehicular activity (EVA) on the lunar surface. Can’t get to an event this weekend? You can still go outside no matter where you live and look at our incredible neighbor. For a list of Moon phases and other cool Moon facts, check out the NASA Science Earth’s Moon page.