The Hunter’s Moon will be appearing in the northern hemisphere on Sunday, October 9th this year. It always follows the Harvest Moon, the full moon that appears closest to the autumnal equinox.
Hunter’s Moon; 120 stacked shots for color and depth by Luis Argerich, Nov 2012
Full moons occur when the sun and moon are on opposite sides of the Earth. A full moon is almost 12 times brighter than a first or third quarter moon. The Harvest Moon’s name signifies that farmers working to bring in their crops will have enough light in the evening to work a few additional hours each day. After the harvest is complete, and fields are more open and easier to hunt in, the Hunter’s Moon will provide a few extra hours to kill enough prey to stockpile a family’s winter larder.
Hunter’s Moon in the afternoon by Jeffery Grandy, Oct 2015
In autumn, the path of the moon, known as the ecliptic, makes a narrow angle with the horizon and shortens the amount of time between the setting sun and the rising moon. At this time of year, the moon rises 30 minutes later each evening instead of 50 minutes later as it does the rest of the year. It will be particularly bright for several nights before and after the actual full moon, providing about two weeks of extra harvesting or hunting time.
The moon takes 27.3 days to orbit the Earth, but with the Earth orbiting the sun in the same direction, it actually takes 2.2 days longer for the moon to get back to the same point in the sky. A lunar month, 29.5 days long, is the time it takes for the moon to return to the same place. In our calendar, only February is shorter than 29.5 days, so each month typically has one full moon. A second full moon in one month, called a blue moon, occurs every 2.7 years, and no full moon in February occurs every 19.5 years. The next time there will be a month without a full moon will be in 2037.
Hunter’s Moon over Cleveland by Erick Drost, Oct 2019
When the moon rises, it looks huge, but this is only an illusion. To prove this to yourself, take a small object, such as a bottle cap and with one eye closed, hold it at arm’s length in front of you, covering the moon. Note how small or large the object is in relation to the moon. Do this when the moon is on the horizon and later when the moon is high in the sky. The object and moon will be the same size relative to each other at both viewing times. A full moon covers the same area of sky at all times during the night and no one full moon is any bigger or brighter than any other.
Hunter’s Moon while we sleep by Rebecca Suchland, Oct 2013
A full moon may have a reddish-orange tinge when it is close to the horizon. This is due to the extra amount of atmosphere between you and the moon compared to when it is straight over your head. The Earth’s atmosphere scatters blue light, but it lets red light waves through, giving the moon a reddish tinge.
How many stars can you see from your backyard tonight? In a dark sky, far away from any light, about 4500 stars can be seen with our naked eye. In contrast, when viewing night skies from a city like Chicago, we can see only about 35 stars. Adding binoculars or a small telescope will greatly increase the number of stars and the detail you can see.
Orion constellation, by G.Tzevelekos, Nikon and StarAdventurer
Fall, winter, and spring, during the months of standard time, is called the “observing season” by astronomers. Winter months give us long nights and short days. Earth’s northern hemisphere is tilted away from the sun, significantly reducing the length of time for morning and evening twilight. At this time of year, it gets dark late in the afternoon, providing many hours of stargazing time. Also in winter, cold air holds less moisture than warm air, yielding clearer skies without any haze.
Mercury by NASA
Saturn by NASA
Factors to consider when choosing a time and location to go stargazing is the brightness of other lights in the area. On cloudless nights, a full moon can be bright enough to light up the sky and hide a majority of the stars from view. Observing the night sky is best during the few days before, during and after a new moon, which occurred this month just a couple of days ago, on January 12th. Other sources of light obscuring our visibility are man-made. The farther away from these areas you can get, the better your observing experience will be. This is a spectacular time of the month when, depending on your location, hundreds of stars may be visible with the naked eye. With assistance from binoculars or a telescope, faint objects such as galaxies, nebulae and star clusters will also be visible.
When the northern hemisphere is experiencing summer, at night the Earth faces towards the center of our galaxy, with the 300 billion stars of the Milky Way. In winter, Earth has traveled to the opposite end of its orbit, and during the night, it faces outward towards the farther reaches of the galaxy. Stars are being displayed against a much darker background, making it easier to see individual stars, constellations and planets. Many sites out of the city, especially State or National Parks and recreation areas, have far fewer visitors in winter months, contributing less light pollution and less competition for viewing locations. Check for hours on their websites.
Jupiter by NASA
Neptune by NASA
What’s visible right now in our neighborhood? There are several good online sites with information for what to view and when to look for it. Plus they provide good descriptions and other information. But the best way to learn about this aspect of nature is to get out and see it yourself. Check the weather for clearer nights and check some of the sites listed below for moon phases in the coming weeks.
Mars by NASA
Uranus by NASA
Planets that are easily viewed tonight include Mars from sunset to 1:00am in the west-south-west; Uranus in the south drifting westward from sunset to 1:30a; Neptune in the south-west from sunset to about 9:00pm. Uranus and Neptune are very faint, but your view can be greatly improved with binoculars of 7x power or better. Mercury, Saturn and Jupiter can be seen with your naked eye, clustered low in the west-northwest sky, in the constellation Capricornus, for about an hour after sunset for the next few days.
Here is a list of websites with basic information that can get you started:
Thanksgiving has come and gone, and we are moving into late autumn and starting to think about winter snows. As we enjoy autumn activities, the earth is moving ever closer to the sun. In January, the earth will be at its closest approach to the sun than any other time of the year. So, why are we in the deep freeze at that time?
The earth’s axis is a straight line passing through both the north pole and the south pole. In relation to the sun, the axis is tilted 23.5˚ to one side. Referring to our diagram above, called “Earth Axis”, the subsolar point is where the sun’s rays directly hit the earth at right angles. The northern hemisphere is tilted away from the sun during winter in our area, when the light and warmth of the sun is striking the earth at an oblique angle, compared to the much more direct sunlight striking the earth in the southern hemisphere’s summer.
The tilt of the axis changes slightly every year causing a wobbling movement. The wobble is called axial precession and can be visualized by watching a spinning top as it moves across a floor, not quite perfectly smooth. As the top moves in circles, so does the wobble of the earth, taking about 26,000 years to return to the same orientation. Earth’s spin drifts slowly east and west, but never very far. The farthest movement observed from the center of the axial spin, since recording began in 130 B.C., has been 37 feet. This will not affect daily life but does affect GPS and satellite observations.
There are many theories about what causes axial precession, but data from the last five to seven years shows a strong possibility that movement of water around the world is responsible. Changes in the amount of water and ice can be counted as changes in mass and weight. These types of changes near the poles have no significant effect on the earth’s spin, but where these changes occur in the middle latitudes, around 45˚, greatly impacts the stability of the spin. Losses of water in the Europe-Asia-India areas has created an imbalance in mass and weight sufficient to alter earth’s spin and account for some of the recent wobble movements. There are strong correlations with other water movements back through the last 2,150 years of history.
As the earth moves through a one year orbit around the sun, the tilt of earth’s axis does not change. As shown in the diagram labeled “Earth Orbit”, this means that for a quarter of the year, the northern hemisphere is leaning towards the sun. In mid-June, the summer solstice occurs when earth’s tilt and orbit brings the northern hemisphere closest to the sun, and we experience the longest daylight period. The winter solstice, occurring in mid-December, is when the southern hemisphere is closest to the sun, and the northern hemisphere experiences the shortest day of the year. The two in-between periods, vernal (spring) and autumnal (fall) equinox are when the sun’s orbital path crosses the equator, and day and night hours are about equal.
The Full Harvest Moon occurred last night at 6:31pm, but you can still observe it for the next couple of days. The moon takes 29.53 days to complete one full orbit around the earth. During that time it passes through eight phases, each lasting a little less than 4 days. A phase is determined by where each of three bodies are positioned: the sun, the moon, and the earth. The angle of the moon from each of the other two determines what phase of the moon we will see. What we see of the moon is due to sunlight reflected from the surface of the moon back to the earth.
Moon, Smokies National Park by DonArnold
The moon does not rotate as it proceeds along its orbit around the earth, so we are always looking at the same side of the moon. There is an excellent presentation of how the phases of the moon are seen from earth provided at: https://www.timeanddate.com/astronomy/moon/location.html. The phases include:
New Moon: the moon is between the earth and the sun, so no light is reflected back to the earth and the moon is not visible.
The Waxing Crescent is visible as the moon moves eastward and an observer starts to see a small slice of the moon’s surface. As the visible crescent grows larger each night, it is called waxing which means to increase gradually.
First Quarter is when the moon is one-quarter of the way around its orbit.
The Waxing Gibbous Moon is more than half full but not totally full.
The Full Moon shows us the completely lit side that faces the earth
The Waning Gibbous Moon is still more than half lit, but waning refers to a gradual decrease in the visible side.
The Third Quarter Moon is when the moon is three-quarters of the way around, now located on the other side of the night sky.
The Waning Crescent phase shows the remaining small slice of the moon before it once again moves to a New Moon and the lighted surface is no longer visible to an observer.
As you can see from the presentation on the web site above, the moon’s orbit is elliptical, but sometimes it is closer to earth, sometimes farther. The path that it follows is called the Metonic Cycle, and it is repeated every 19 years. It was discovered in 432 B.C. by the Greek astronomer, Meton of Athens. Due to slight variations in the moon’s travel as well as the slowing rotation of the earth, the cycle may be off by 1 day in some 19-year periods and then return to the same day in other periods.
When there are two full moons in a month, we call the second one a Blue Moon. Blue Moons occur once every two to three years. This month, the Blue Moon will appear on Halloween night, an occurrence that will not happen again for another 19 years. The exact time of the Blue Moon will be October 31, 2020 at 9:49 am.
Moonscape, Aug95 by DonArnold
Folklore from Native Americans, settlers, and indigenous people of western Europe has introduced many other names for each of the monthly full moons throughout the calendar year:
January – Wolf Moon: Native Americans believe that wolves hunt around villages on cold winter nights and howl at the full moon.
February – Snow Moon: This marks the month of the heaviest snowfalls.
March – Worm Moon: As the ground thaws, earthworm start to appear. Settlers colonizing early U.S. areas also call this the Lenten Moon, marking the last full moon of winter.
April – Pink Moon: Spring rains bring wildflowers into bloom including an herb called ‘moss pink’ or ‘wild ground phlox,’ Phlox subulata.
May – Flower Moon: It marks the spring time bloom.
June – Strawberry Moon: Strawberries are only ripe for a short period at this time of year.
July – Buck Moon: It marks when antlers covered in velvet are first seen on mature bucks.
August – Red Moon: Due to the haze caused by high humidity, the moon takes on a red tinge.
September – Harvest Moon: The full moon that occurs closest to the autumnal equinox when the sun’s trajectory crosses the equator and nights become longer than days.
October – Hunter’s Moon: Now is the time for hunting fattened deer for winter stores. Hunter’s Moon is an important feast day for Native Americans and most of western Europe.
November – Beaver Moon: It marks the time to set traps for beaver, before winter freezes all of the waterways.
December – Long Night’s Moon: At this time of year, the moon has the longest and highest trajectory above the horizon.
All solar bodies including stars, planets and moons have gravity. Gravity extends outward from every solar body for some distance depending on the mass of each solar body and how far two bodies are apart. The moon’s gravity pulls at everything on the earth, effectively stretching the earth toward the moon and squashing the earth at right angles to the moon.
As water is also pulled and squashed, a bulge in the world’s oceans develops on the side of the earth facing the moon as well as on the opposite side. The earth rotates under each bulge, and high tide occurs as the bulge passes over a shoreline. Thus, there are two high tides each day.
As the earth rotates under the oceans, friction with the water slows down the earth’s rotation a fraction of a second each century. This does not really affect us, but in 100 million years, a day will last 30 minutes longer. At the same time, the moon’s orbital speed is increasing a fractional amount. In that same 100 million years, the moon will spiral ever farther from the earth, and it will be an average of 3000 kilometers (1864 miles) farther away from the earth. As we look into the past, these same effects have been present since the moon was created some 4.5 billion years ago.
An example of the effect this friction has had on earth and the moon comes from a study of coral reefs. A coral reef is made up of millions of tiny animals called polyps. Each day, polyps deposit a layer of calcium to a coral reef. Scientists have been able to count the layers of calcium to determine the age of a reef, including fossilized coral from the Devonian period. When counting the layers of fossilized coral, the number of layers present is much higher than the sum total of days in that period. We can account for this difference by calculating how much faster the earth was rotating in the past. The results show us that a day in the Devonian period lasted about 22 hours, and there were 400 days in a year accounting for the extra layers of calcium in the fossilized coral.
Moonscape, Jun87, by DonArnold
Luna, from the Latin lucere, meaning to shine was the Roman goddess of the moon, animals and hunting. Her symbol is a crescent ☾. The word luna and the word moon were used in common language for many hundreds of years to describe our neighboring satellite. In 1919, the first meeting of the newly formed International Astronomical Union was held, and the name was standardized to “moon”. This month we will experience all phases of the moon, including a Harvest Moon and a Blue Moon. You can track moonrise, moonset and phases by date and time, plus lots of other lunar information, from the Time and Date website. I hope you find Halloween to be an enjoyable and interesting time this year.
