Stargazing in the September Skies

by Cam Wipper, CFHT remote observer

What You Need: Just your eyes! Everything in this guide can be seen with nothing more than your very own eyes. No special equipment required.

Where To Go: We here on the Big Island are blessed with some of the greatest night skies on Earth. You can find many of the targets listed here from your own backyard. Of course, if you live in Waimea, Hilo or Kailua, the lights of your town can make fainter objects more difficult to see. The best locations are those far from light sources. Some of my favourite locations are Pu’u Huluhulu off of Saddle Road (across from the Maunakea Access Road), along Chain of Craters Road in Hawai’i Volcanoes National Park (remember: there is no entrance fee after 8pm— perfect for stargazers) and along Mana Road on the slopes of Maunakea.

Surprisingly, the summit of Maunakea, though unbeatable for telescopes, is not the best site for human observers. Due to the thinness of the air, and resultant dearth of oxygen, at the altitude of the summit, human night vision becomes far less efficient than at altitudes closer to sea level. For this reason, it is best to stargaze no higher than 10,000 feet (3000 m). The Maunakea Visitor Information Station is an example of a site located near this elevation.

Moon phases for September 2016 in Waimea.
Moon phases for September 2016 in Waimea.

What To Look For: September is a fairly quiet month for stargazing in Hawaii. We have no meteor showers and both the eclipses occurring this month—an Annular Solar Eclipse (Africa) and a Penumbral Lunar Eclipse (Eastern Hemisphere)—are not visible from Hawaii. Despite missing out on these events, we still have plenty to observe; we do, after all, and some of the greatest night skies on Earth!

We will start in the early evening low in the western sky. In the first week or so of September we can find the two brightest planets chasing the Sun into the horizon. Look low and you will find Jupiter and Venus. Jupiter—the largest planet in the solar system—and Venus—the closest planet to Earth—are both extremely bright. Jupiter is the fourth brightest object in the sky; only outshone by Venus, the Moon and, of course, the Sun. It is common knowledge that the Sun and Moon cast shadows, but it is less well known that Venus can cast shadows too. These shadows, rarely seen, are extremely delicate and are more easily seen in long-exposure photographs, than by the naked eye. Nevertheless, it is possible to be illuminated by the reflected sunlight from our sister world.

Jupiter, Mercury and Venus in the evening sky on Aug 14th. The month, Venus and Jupiter will be very bright and close to each other. photo credit: Seth Buckley
Jupiter, Mercury and Venus in the evening sky on Aug 14th. The month, Venus and Jupiter will be very bright and close to each other.
photo credit: Seth Buckley

These are not the only planets visible. Once Jupiter and Venus have set (and they will set early), look high into the southwest. Here you will find the planets of Mars and Saturn as they form a beautiful triplet with the red supergiant star Antares. They appear together in the sky nearby to the constellation Scorpius, also known as Maui’s Fishhook here in Hawaii. Antares is a red supergiant star and can often be mistaken for Mars due to its brilliant red color. In fact, the names “Antares” means, “equal-to-Mars”, though it is more commonly known as ‘the Heart of the Scorpion’ for its position in Scorpius.

Moving on to stars:

Sunrise and sunset times for Waimea.
Sunrise and sunset times for Waimea.

Visible as soon as the sky is dark is the center of the Milky Way itself. Just below Saturn and Mars, between Scorpius and its’ neighbor Sagittarius is the brightest part of the Milky Way. When we look in this direction, we are seeing the faint, combined light of billions of stars, all packed densely into the core of the galaxy. We can also see dark ribbons of gas and dust, nebulosity of the same material that made the stars and planets we know today. It is just about the last chance to see the Milky Way for this year, so if you haven’t seen it yet, now is your final opportunity!

Also visible this month, in the early evening sky is the beautiful star: Arcturus. As the fourth brightest star in the night sky, it is highly visible and part of the Greek constellation of Boötes. While, a prominent star in Western astronomy, this star has extra significance here in Hawai’i. In the islands, it is known as Hōkūleʻa, the “Star of Joy”. Hōkūleʻa is the zenith star, or the star that passes directly through the highest point in the night sky, here in the Hawaiian Islands. Because of this, it could be used by ancient Polynesian and Hawaiian navigators as a guide to the Hawaiian Islands, when voyaging up from more southerly islands like Tahiti or the Marquesas Islands. Hōkūleʻa is also part of the largest of the Hawaiian Starlines, Ka Iwikuamo’o, “the backbone” of the sky.

'Imiloa's sky map of Kaiwikuamo'o
‘Imiloa’s sky map of Kaiwikuamo’o

This starline also contains one of the most special objects visible in the Hawaiian skies—Hōkūpa’a. The name Hōkūpa’a means “fixed star”—hōkū, the name of our CFHT newsletter, is “star” and pa’a is “stuck or firm”—and this is a very good name for this object. Of all the stars in the sky, this is the only one which does not move. You may know it as Polaris, the North Star. Polaris is not an extremely bright star, though it can be found by connecting the two stars at the end of the scoop portion of the Big Dipper—also part of Ka Iwikuamo’o known as Nã Hiku, “the Seven”—and then continuing that line into the north. This will point directly to the Polaris.

Polaris can be used to determine the latitude of your location on Earth. Since it is (almost) directly above the northern celestial pole, it’s elevation above the northern horizon from a given location on Earth matches that same location’s latitude north of the equator. For example, here on the Big Island, which is between 19°N and 21°N latitude, Polaris appears ~20° above the northern horizon at the end of the handle of the Little Dipper.

All the way at the other end of Ka Iwikuamo’o, we find the one of my personal favorite night sky objects: Hãnaiakamalama here in Hawai’i. It is known as the Southern Cross in most other parts of the world. Hawai’i is the only one of the fifty U.S. states that the Southern Cross can be viewed from, it is getting very hard to see now, but you may just be able to spy it setting low in the southwest immediately following sunset.

Now most of what was previously mentioned, is only visible in the early evening. If you’re up late, what can you find?

At around 2:00am, one of the most famous constellations rises in the east: Orion. The famous Belt of Orion is one of the easiest night sky features to find. Look for a vertical row of three bright stars almost due east. To the north of them you will find Betelgeuse, a huge red supergiant star nearing the end of it’s life. To the south, you will see Rigel, a blue-white supergiant, estimated to be around 200,000 times more luminous than the Sun. These two stars are the ninth- and seventh-brightest stars in the night sky respectively.

Rising just before Orion is Taurus, the Bull. Taurus contains the bright red star, Aldebaran, often called the “Eye of the Bull”. Greek mythology describes Taurus and Orion as fighting in the sky, with Taurus defending the Seven Sisters from Orion’s rather lustful advances.

These sisters, in reality a stunning group of stars known as an Open Cluster, can be found as well. They are more commonly known as the Pleiades, and are positioned just above Taurus. A quick way to find them is to locate Betelgeuse. Then trace a line in the sky to connect Betelgeuse with Aldebaran. Finally continue that line past Aldebaran, and you will come to the Pleiades.

The Pleiades are well known across the Northern Hemisphere for their beauty and cultures around the world have their names for the group. In Hawaii, they are known as Makali’i, and they are mentioned several times in the Kumulipo, the Hawaiian Creation Chant, including on the fifth line of very first verse.
In Japan they are known as Subaru, a name which graces not only a successful automobile manufacturer (now you know their logo is stars!), but also a telescope on Maunakea, which as you may guess, is owned by Japan. Also visible are the constellations of Cassiopeia, Perseus, Andromeda, Pegasus, Cepheus and Cetus, the characters of one of my favorite Greek myths…but we’ll get to that next time!

With that, I wish you clear skies and happy stargazing!

If you have any questions, comments or are new to stargazing and would like some tips on getting started, email me at wipper@cfht.hawaii.edu . Aloha!

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