July 2025 Sky Watch
Featured Maunakea Observatory Discovery
Astronomers using data from the W. M. Keck Observatory on Maunakea, Hawaiʻi Island discovered the most energetic cosmic explosions discovered to date, naming the new class of events “extreme nuclear transients” (ENTs). These extraordinary phenomena occur when massive stars—at least three times heavier than our Sun—are torn apart after wandering too close to a supermassive black hole. Their disruption releases vast amounts of energy visible across enormous distances.
The immense total energy output of these ENTs are truly unprecedented. The most energetic ENT studied emitted an astonishing 25 times more energy than the most energetic supernovae known. While typical supernovae emit as much energy as the Sun does in its 10 billion-year lifetime, ENTs radiate the energy of 100 Suns.
Drawing on observations from a wide array of ground- and space-based telescopes, the team determined these extraordinary events could not be supernovae because they release far more energy than any known stellar explosion. The sheer energy budget, combined with their smooth and prolonged light curves, firmly pointed to an alternative mechanism: accretion onto a supermassive black hole.
However, ENTs differ significantly from normal black hole accretion, when materials surrounding the black hole heat up and emit light and typically show irregular and unpredictable changes in brightness. The smooth and long-lived flares of ENTs indicate a distinct physical process—the gradual accretion of a disrupted star by a supermassive black hole.
The rarity of ENTs, occurring at least 10 million times less frequently than supernovae, makes their detection challenging and dependent on sustained monitoring of the cosmos. Future observatories like the Vera C. Rubin Observatory and NASA’s Nancy Grace Roman Space Telescope promise to uncover many more of these spectacular events. Maunakea observatories will provide extreme precision for characterizing these ENTs, which will revolutionize our understanding of black hole activity in the distant, early universe.
More information can be found at this press release from Keck Observatory: https://keckobservatory.org/ents/
Special Events
Lāhainā Noon
Hawaiʻi residents will be treated to a unique solar phenomenon in July known as Lāhainā Noon, when objects will briefly lose their shadows as the Sun passes directly overhead through the center of the sky. Due to its proximity to the equator, Hawaiʻi experiences Lāhainā Noon twice a year — once in May and once in July — in the months before and after the Summer Solstice. This phenomenon only occurs in tropical locations on Earth.
Lāhainā Noon occurs on different dates and times in the Hawaiian Islands due to slight changes in latitude. For example, Lāhainā Noon will take place at 12:30 p.m. July 24 in Kailua-Kona and 12:26 p.m. July 24 in Hilo, even though both towns are located on Hawaiʻi Island. In Honolulu, Lāhainā Noon will occur at 12:37 p.m. May 15.
The exact moment of Lāhainā noon, when the Sun is at the exact center of the sky, will only last a moment. At ʻImiloa, our mosaic “Voyage of the Navigator” is positioned exactly under our sky light so that during Lāhainā noon the mosaic is perfectly illuminated by the sky light above.
Delta Aquarids Meteor Shower
The Delta Aquarids Meteor Shower is produced by debris left behind by comets Mardsen and Kracht. The shower peaks the night of July 28 and morning of July 29. Best viewing will be from a dark location after midnight. Meteors will radiate from the constellation Aquarius but can appear anywhere in the sky.
Evening Observing
At sunset the two starlines that will be present in our night sky will be Kaʻiwikuamoʻo in the western half of the night sky and Mānaiakalani in the east. They are our summer and fall starlines. After sunset, as we look toward the direction of hikina (east), we can still see Humu (Altair), Keoe (Vega), and Piraʻetea (Deneb) rising in the star houses of Manu Koʻolau and Lā Koʻolau, forming our “Navigator’s Triangle.” South of our celestial equator, we can observe Mānaiakalani (Scorpio) rising across the houses of ʻĀina Malanai, Noio Malanai, and Manu Malanai.
Morning Observing
At 5am Kalupeakawelo Will be at the zenith of our early morning Hawaiian sky. Setting in the west will be Mānaiakalani with the last star we can see of that starline being Piraetea(Deneb). Rising in the east will be Kekāomakaliʻi with the sunrise beginning in ʻāina koʻolau. You are also able to see Saturn, Venus and Uranus in our early morning skies.
