Monthly Sky Charts for Hawaiʻi
July 2019 Skywatch
Saturday, July 20 marks the 50th Anniversary of the Apollo 11 moon landing, the first time humans were able to leave Earth behind and set foot on another world, famously proclaiming “That’s one small step for a man, one giant leap for mankind.” Celebration events will occur across the islands, including ‘Imiloa’s Moon Landing Celebration at ‘Imiloa Astronomy Center on Saturday, July 20th from 10am-3pm.
Featured Maunakea Discovery
As we celebrate the in-person exploration of our own moon, we continue to observe and explore the other moons of the solar system using our observatories, including those here in Hawai‘i. Using data taken with the W.M. Keck Observatory accompanied with visible-light observations with the Hubble Space Telescope, astronomers took a look at the notable surface features of Europa, Jupiter’s enigmatic icy moon, and found… table salt.
Europa has intrigued astronomers for decades. Since we first got close up looks at the moon with the Voyager and Galileo spacecraft, we have observed strong evidence of a subsurface ocean on the moon. The presence of this ocean leads many astro-biologists to consider Europa to be the most likely place for us to find life elsewhere in our solar system. In a research article published last month titled: “Sodium Chloride on the Surface of Europa,” astronomers have detected the presence of salt on the surface. While we often think about table salt as a needed ingredient for our cooking, salt is also an essential component of our ocean water. This discovery suggests that Europa’s ocean may be very similar to Earth’s ocean; and as we know here in Hawaii the ocean is full of all forms of life. Read more about this discovery and Keck Observatory’s contribution here: http://www.keckobservatory.org/europa-salt/
Evening Observations
In our early evening hours we will be able to view two of our great navigational starlines. Kaiwikuamo‘o will still be stretching over our heads connecting the north star, Hokupa‘a, down to the Southern Cross, Hanaiakamalama. July will be our last month this year where we can see the southern cross in our early evening sky. At the same time our summer starline, Manaiakalani will be rising in the eastern sky.
During our summer months in Hawaii we get a truly spectacular view of the milky way galaxy. In the early evening, when we look towards the shape of Kamakuanuiomāui, Maui’s Fishhook, we see an area of the Milky Way band commonly called “the bulge”. As we look towards the bulge we are looking towards the central regions of the Milky Way. The whole band of the Milky Way is illuminated by the combined light of millions of stars, most of them are too far away for us to see their individual points with our naked eyes but by using a small telescope or even a pair of binoculars observers will see a multitude of stars in the Milky Way band. On clear dark, moonless nights with little light pollution this band will stand against our dark night.
Rising in Manu Malani, South East, will be the notable planets of Jupiter and Saturn. Jupiter, being the largest of the gas giant planets, is also one of the brightest objects in our night sky and will stand out against the backdrop of the Milky Way. Saturn will be at its brightest on July 9th when it will be at opposition. Opposition is when an outer planet (planet further from the sun than Earth), is lined up with the Earth and the Sun, on this date the planet is at its closest physical position to Earth. On this night Saturn will rise at the same time as the Sun sets and will be in the sky throughout the entire evening.
Morning Observations
In early July the Sun will be rising just before 6 am and dawn will begin to color our skies at around 5:30 am. Early birds viewing the sky at this time will see a very different sky. At this time observers will be able to catch the notable Makali‘i, Pleiades, star cluster rising out of the east. Trailing behind this famous open cluster we can catch the famous shape of Heihieonakeiki, Orion, rising exactly in the east just before the sun rises.