September Astronomy: What's in the North Texas sky this month?

What’s happening in the skies over North Texas this month? September holds some spectacular sights in the night and morning sky. Check out the list below.

THE SUNSET PLANET, VENUS

Venus is visible in the western sky for up to an hour after sunset. On Sept. 4, a waxing crescent moon is less than 5° west of Venus. On Sept. 5, they switch places, now 7° apart with the moon southeast of Venus. The pair is still 5° high 30 minutes after sunset.

By mid-September, Venus remains quite low after sunset. Venus during the last few days of September, stands 7° high in the western sky, 30 minutes after sunset and remains visible for nearly another hour.

Venus’s distance from the Earth varies from 24 million miles to 162 million miles. Mars averages a distance from the Earth of 140 million miles. The closest recorded distance to Mars from Earth was recorded in August 2003 when the two were 34.8 million miles apart. According to NASA, the two will not be that close again until the year 2237.

MORNING PLANETARY DELIGHT

The pre-dawn hours will feature six planets. Keep an eye on Mercury, Mars, Jupiter, Uranus, Neptune and Saturn in the hours before sunrise. The planets always appear lying along the ecliptic, which is the plane of our solar system.

Mercury is 48 million miles away from Earth when they are at their closest. The maximum distance between the two when they are on opposite ends of their orbits is 137 million miles.

Mars averages a distance from the Earth of 140 million miles. The closest recorded distance to Mars from Earth was recorded in August 2003 when the two were 34.8 million miles apart. According to NASA, the two will not be that close again until the year 2237.

Jupiter’s distance from the Earth varies from 336 million miles to 600 million miles.

Saturn’s distance varies from the Earth. When the two are closest, they lie approximately 746 million miles apart, or eight times the distance between the Earth and the Sun.

At their most distant, when they lie on opposite sides of the Sun from one another, they are just over a billion miles apart, or 11 times the distance between the Earth and the Sun.

When Neptune and the Earth line up on the same side of the Sun, at their closest, they are only 2.7 billion miles apart. But when the planets are on opposite sides of the Sun, they can put as many as 2.9 billion miles between them.

FOLLOW THE ZODIACAL LIGHT

During the September pre-dawn, a glow caused by millions of tiny dust particles filling our inner solar system can be observed on clear moonless nights from very dark locations. The zodiacal light is a faint cone-shaped glow. This zodiacal light shines with similar or a bit fainter brilliance than the Milky Way and is located along the ecliptic, which is angled steeply to the horizon this month, improving your chances of seeing it.

The first two weeks of September are the most favorable time this month to view this phenomenon. Any glow from the urban lights of Dallas-Fort Worth will limit the view.

PEAK OF THE ε-PERSEID METEOR SHOWER

September is not known for its meteor showers. From Sept. 5 through Sept. 2, the ε-Perseids meteor shower runs. Despite their name, these meteors are not caused by the same comet, Swift-Tuttle, as the August Perseids. They simply appear to radiate from the same point in the night sky –which is how meteor showers get their names.

At their maximum, you can look for roughly five ε-Perseids per hour, coming from the general area of the constellation Perseus high in the southwest sky.

The ε-Perseids can be seen from anywhere in the Northern Hemisphere. You are more likely to see them if you have an unobstructed view with clear skies in a very dark place far from any urban light sources.

WHEN DOES THE INTERNATIONAL SPACE STATION FLY OVER NORTH TEXAS?

The International Space Station will make flybys across the North Texas sky this month. The ISS appears as a fast-moving star across the night sky.

The ISS rotates around the Earth at a speed of 17,500 mph. The ISS rotates about its center of mass at a rate of about four degrees per minute so that it will complete a full rotation once per orbit. This allows it to keep its belly towards the Earth. One revolution around the planet takes about 90 minutes (16 per day).

Also, the ISS sits at an altitude of 250 miles above the Earth. By the way, that is 1.32 million feet. Most commercial airplanes fly between 33,000 to 42,000 feet.

A SEPTEMBER FULL MOON

On Sept. 17, there is a full moon.

This full moon is called the “Corn Moon.” It gets its name after the time of year that corn is harvested.

It is also called the “Harvest Moon.” This is given to the full moon closest to the fall equinox. The reason why the Harvest Moon varies is that the lunar month doesn’t line up with the equinox. Usually, the closest full moon occurs in September, but every three years or so, it falls in October. When the October full moon is not a Harvest Moon, it is known as the Hunter’s Moon.

Other names refer to the “Autumn Moon”, “Child Moon”, “Falling Leaves Moon”, “Yellow Leaf Moon” and “Mating Moon.”

MOON PHASES

Also, check out other phases of the moon this month.

On Sept. 18 at 8:23 a.m. CDT., the moon will be at perigee, it is closest to the Earth for this orbit at 222,007 miles.

On Sept. 5 at 9:53 a.m. CDT., the moon will be at apogee, its farthest from the Earth for this orbit at 252,408 miles.

THE SEPTEMBER EQUINOX

On Sept. 22 the seasons officially change. The September Equinox is also called the Autumnal Equinox in the Northern Hemisphere and the Vernal Equinox in the Southern Hemisphere.

It signals the point where the Earth experiences roughly equal lengths of day and night. Also, this will mark the beginning of fall in the Northern Hemisphere and spring in the Southern Hemisphere.

With the passing of the September Equinox, the Earth has traveled 438 million miles around the Sun. The Earth is moving at an orbital speed of 66,616 mph. This speed is fast enough to cover the planet’s diameter in 7 minutes and the distance to the Moon in 4 hours.

THE TRANSIT OF A JUPITER MOON

Ganymede, Jupiter and the solar system’s largest moon will transit across the planet this month.

The moon’s huge shadow crosses Jupiter’s polar region from about 1:45 a.m. to 3:40 a.m. CDT. on Sept. 28.

Please enjoy these events happening in the night sky this month. Until then…Texans, keep looking up!