Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
2018 July 3
An Airplane in Front of the Moon
Image Credit & Copyright: Ji-Hoon Kim
Explanation: If you look closely at the Moon, you will see a large airplane in front of it. Well, not always. OK, hardly ever. Actually, to capture an image like this takes precise timing, an exposure fast enough to freeze the airplane and not overexpose the Moon — but slow enough to see both, a steady camera, and luck — because not every plane that approaches the Moon crosses in front. Helpful equipment includes a camera with fast continuous video mode and a mount that automatically tracks the Moon. The featured fleeting superposition was captured from Seoul, South Korea two weeks ago during a daytime waxing gibbous moonrise. Within 1/10th of a second, the airplane crossingwas over.
Use Big Dipper to find Polaris
Tonight, use the Big Dipper in the constellation Ursa Major the Great Bear to find the sky’s northern pole star, Polaris. This is the star around which the whole northern celestial sphere appears to turn throughout the night. That’s because this star is located nearly above Earth’s northern axis. In times past, wanderers on the northern face of Earth used Polaris to stay on course.
Once you find it, you can also look for Thuban, a famous former pole star in the constellation Draco the Dragon.
So how can you find Polaris? Look at the chart at the top of this post. You’ll simply draw a line through the Big Dipper’s pointer stars – Dubhe and Merak. That line will point to Polaris, the North Star. You can use this trick to find Polaris any evening – no matter how the Dipper is oriented with respect to your northern horizon.
Once you’ve got Polaris, if your sky is dark enough, you might be able to see the Little Dipper asterism. It’s harder to spot than the Big Dipper and needs a dark sky to be seen.
The chart below shows the Big Dipper, Little Dipper and the star Polaris as you’ll see them in the north on July evenings. Polaris marks the end of the handle on the Little Dipper asterism, which is in the constellation Ursa Minor.
In other words, the Little Dipper is not the whole constellation, but just a noticeable pattern within the constellation Ursa Minor the Smaller Bear.
Polaris isn’t the brightest star in the sky, as is commonly supposed. It’s only 50th brightest or so.
Still, Polaris is bright enough to be seen with relative ease on a dark, clear night.
How to find the star Thuban, and its constellation Draco the Dragon. As night deepens, and the fainter stars of the Little Dipper spring into view, those of you with dark-enough skies can expect to see a winding stream of stars between the Big and Little Dippers. These meandering stars make up the constellation Draco.
The star Thuban is one of the stars here, part of the Tail of the legendary constellation Draco the Dragon, a fixture of the northern skies. I always find Thuban by remembering it’s between the Big and Little Dippers.
Thuban is famous for having served as a pole star around 3000 B.C. This date coincides with the beginning of the building of the pyramids in Egypt. It’s said that the descending passage of the Great Pyramid of Khufu at Gizeh was built to point directly at Thuban. So our ancestors knew and celebrated this star.
Bottom line: Draw a line through the Big Dipper pointer stars to find Polaris the North Star. If your sky is dark, look for Thuban in the Tail of Draco the Dragon.
The Words of Confucius
By three methods we may learn wisdom: First, by reflection, which is noblest; Second, by imitation, which is easiest; and third by experience, which is the bitterest.
Crack the Cookie
Your Daily Rune for Today
“Thor-is-as” – Literally: “Thurses” or “Giants” – Esoteric: Strong one, Resistance
Key Concepts: Unconscious forces, sociological forces, Thor, Loki as giant, chaos, destruction by natural forces, complexities of aggression, conflicts, disputes, psychological problems, lightning, breakthrough, aggressive male sexuality, battering down barriers, thorn of awakening, trouble, enthusiasm
Psi: enthusiasm, struggle against unconsciousness, male sexual prowess
Energy: enthusiasm, self-empowerment, chaos, active defensive force, breaker of resistance, destructive storms
Mundane: storms, tools, weapons, conflict
Divinations: Reactive force, directed force, vital eroticism, regenerative catalyst, constructive conflict; or danger, defenselessness, compulsion, betrayal, dullness, disease, explosive violence, annoyance, strife
Destruction of enemies, curses binds and fetters
Awakening of the will to action
Breaking resistance of blockages in body, mind and spirit
Increased potency and prowess in romantic relationships
Understanding of the division and separation of all things
Aiming the use of psychic force
The combination of right/left brain processes for generating powerful realization