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Featured Mauna Kea discovery/observation
Researchers using the Keck Observatory on Mauna Kea have discovered a never-before-seen mechanism fueling enormous auroras in Saturn’s atmosphere. This research has astronomers reassessing their understanding of the auroras of gas giant planets and helps tackle a long-standing question relating to Saturn: Why can’t we easily measure the length of a day on Saturn?
The researchers were able to detect twin-vortex flows in the upper atmosphere near the pole of Saturn. These vortices rotate around and drive currents within the ionosphere, which will then reach out to the surrounding magnetosphere, producing bright aurora.
Read more about this groundbreaking research at keckobservatory.org/saturn-aurora.
Special events
Near the end of April, observers will be able to witness the shooting stars of the Lyrids meteor shower.
The debris that creates the annual Lyrids meteor shower came from the tail of a long-period comet, C/1861 G1 (Thatcher), which passed Earth’s orbit in 1861 and will not approach the inner solar system again until 2283.
The Lyrids meteor shower is the oldest known shower ever recorded, as chronicled in the Zuo Zhuan in 687 B.C. This year’s shower is expected to occur April 16 to 25, but the best time to see the meteors will be in the early morning hours of April 22. At its peak there could be about 20 shooting stars per hour, or approximately three meteors a minute.
Evening observations
During the early evening hours of April, stargazers will be able to observe two of the four navigational starlines at the same time.
Kekaomakali‘i (the Bailer of Makali‘i) stretches overhead in the western sky. The great celestial bailer starts in the north with the hexagonal shape of Hokulei, a lei of stars, then passes in a gentle arc through the stars Nanamua and Nanahope. From there it goes to Puana and then the brightest star in the evening sky, ‘A‘a, before dropping down to to Keali‘iokonaikalewa to form the handle of the bailer.
A bailer is used to scoop out water that might be flooding a canoe; however, Kekaomakali‘i is not a bailer for water, but a bailer for the stars. Over the course of the night, the celestial bailer will scoop up the stars from the horizon in the east, scatter them overhead and carry them to the west. The bailer will scatter the shape of Heiheionakeiki, and the famous star cluster of Makali‘i, into the Komohana horizon in the early evening.
As Kekaomakali‘i prepares to set, the next navigational star family will rise in Hikina; this will be Kaiwikuamo‘o, the backbone.
Kaiwikuamo‘o is significant as it stretches all the way from Hokupa‘a, the North star, through Nahiku, the Big Dipper. It follows the arc of Nahiku to Hokule‘a and to Hikianalia, then passes through Me‘e where it drops straight down to Hanaiakamalama, the Southern Cross. While Hanaiakamalama is not visible at 8 p.m., the cross will begin to rise around 9. As the full star family stretches from Hokupa‘a, the North Star, all the way to Hanaiakamalama, the Southern Cross, the entire starline can be viewed only across the latitudes of the northern tropics.
Morning observations
As the planets continue their cosmic dance in the early morning sky, observers will be able to witness a number of planetary conjunctions through the first half of the year.
In March we were able to witness three planetary conjunctions in the early morning sky; in April we will see two planetary conjunctions.
A conjunction is when two celestial objects, typically planets, appear to be extremely close to each other in the sky from our perspective on Earth. In ancient times, the conjunction of planets was considered to be a very significant event as the motion of the planets was thought to predict the future. While conjunctions are not considered to be scientifically significant today, they do make for beautiful events as two planets will appear to merge into one light.
The first conjunction for April will occur during the first week. Planets Mars and Saturn will slowly approach each other, and on the morning of April 4, they will have their closest approach and be less than 1 degree away from each other. Mars and Saturn will rise together at 3:40 a.m. and will accompany each other through dawn until around 6 a.m., when the light of dawn will outshine the two fainter planets.
The second conjunction will be quite dramatic as it will involve Venus and Jupiter, two of the brightest celestial objects we can see in the sky. Through the last week of April, the planets will inch closer to each other in the early morning sky, and on the morning of April 30, the two planets will be less than 1 degree apart. With our naked eye, the planets will appear to merge into one light. However, with a pair of binoculars or a telescope, observers will be able to see the two individual planets next to each other.
Observers watching this unique event with a telescope will be able to see some of Jupiter’s largest moons and the current phase of Venus.
The two planets will rise together at 3:50 a.m. and will be a bright beacon in the east throughout the early morning sky. Dawn will likely start to obscure the two planets by 5:45 a.m. as the sun rises.
One more conjunction will occur with the dancing planets in the early morning sky at the end of May which we will discuss in the next installment of Skywatch; this last conjunction will involve Mars and Jupiter on May 28.
As we watch this series of conjunctions, we are studying the stars in the ways that people did long before telescopes. By tracking these planets, we take note on which planets “move” the fastest in the sky and can use this information to determine which planets are closest and farthest from the sun and from us.
April 2022 Sky Chart by Honolulu Star-Advertiser
The ‘Imiloa Astronomy Center of Hawaii is a center for informal science education at the University of Hawaii at Hilo showcasing astronomy and Hawaiian culture as parallel journeys of human exploration.
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