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.
2016 April 29
Explanation: If you could only see gamma-rays, photons with up to a billion or more times the energy of visible light, the Moon would be brighter than the Sun! That startling notion underlies this novel image of the Moon, based on data collected by the Fermi Gamma-ray Space Telescope’s Large Area Telescope (LAT) instrument during its first seven years of operation (2008-2015). Fermi’s gamma-ray vision doesn’t distinguish details on the lunar surface, but a gamma-ray glow consistent with the Moon’s size and position is clearly found at the center of the false color map. The brightest pixels correspond to the most significant detections of lunar gamma-rays. Why is the gamma-ray Moon so bright? High-energy charged particles streaming through the Solar System known as cosmic rays constantly bombard the lunar surface, unprotected by a magnetic field, generating the gamma-ray glow. Because the cosmic rays come from all sides, the gamma-ray Moon is always full and does not go through phases. The first gamma-ray image of the Moon was captured by the EGRET instrument onboard the Compton Gamma-ray Observatory, launched 25 years ago.
Last quarter moon rises around midnight
onight – April 29, 2016 – the moon won’t rise over your eastern horizon until late, likely after midnight. Given clear skies, you should easily see the moon in the morning sky, even after sunrise, on April 30. The moon will be at or near its half-lit last quarter phase, when the moon’s disk appears half-illuminated in sunlight and half-immersed in its own shadow. It’ll look like the image at the top of this post, which is by Lilliana Mendez of North Bergen, New Jersey.
In the larger view, of course, the moon is always half-illuminated. Now we’re seeing half the moon’s day side, and half its night side.
The terminator – shadow line dividing the lunar day and night – shows you line of sunset on the waning moon. It’s along the terminator that you have your best views of the lunar terrain through binoculars or the telescope.
You might think the half-illuminated quarter moon should be about half as bright as the full moon. But that’s not the case. The last quarter moon is about 1/12th as bright as a full moon. Astronomers say the moon’s rough, sphere-shaped surface accounts for the surprising difference in the amount of moonlight cast by the quarter moon versus the full moon.
Meanwhile – and this might surprise you – the first quarter moon is slightly brighter than the last quarter moon. It shines at about 1/11th a full moon’s brightness (in contrast to 1/12th).
The last quarter moon is slightly less bright than the first quarter moon. That’s because illuminated side of the last quarter moon is more covered over by maria – low lying plains of hardened volcanic basalt.
The dark maria reflect sunlight less effectively than do the lighter-colored lunar highlands.
Bottom line: Watch for the moon at or near its last quarter phase. It’ll likely rise after midnight on the morning of April 30, 2016.
Bruce McClure is the chief writer for the popular EarthSky Tonight pages. Since joining EarthSky in 2004, he has written thousands of astronomy articles, enjoyed here by millions. He also writes, gives planetarium shows and hosts a wide assortment of public astronomy programs in and around his home in upstate New York. If you ask an astronomy question on our site, it’s likely to be Bruce that answers it. His love for the heavens has taken him to Lake Titicaca in Bolivia, and he has sailed the North Atlantic, earning his celestial navigation certificate through the School of Ocean Sailing and Navigation. Bruce is also a sundial aficionado. He says his number one passion – besides his wife Alice – is stargazing.
Article published on EarthSky
The Words of Confucius
The firm, the enduring, the simple, and the modest are near to virtue.
Your Daily Influence
April 29th, 2016
The Devil Reversed
The reversed Devil signifies a spiritual rebirth, freedom from the preoccupation with the secular and the overcoming of pride and selfishness.
Berkano reversed may foretell family problems and dissatisfaction. Your life path my not be clear to you at this time. Be careful to protect that which is yours.
The tortoise represents the dome of the sky, the universe. It tells you to take slow, deliberate steps and you can acheive everything you desire.
Your Daily Influences represent events and challenges the current day will present for you. They may represent opportunities you should be ready to seize. Or they may forewarn you of problems you may be able to avoid or lessen. Generally it is best to use them as tips to help you manage your day and nothing more.
Your One Ancient Charm Card Drawing for the Upcoming Weekend
Ah, The Caduceus, Involves Your Physical Health This Weekend
You will find you have within you the ability to resolve all conflicts and disagreements with regard to this aspect. You will find an eloquence you did not realize before.
A little background on The Caduceus
The staff of Mercury was given to him by Apollo in exchange for the lyre. The rod was endowed with the remarkable power of deciding all quarrels and bestowing wonderful eloquence upon its possessor. Mercury proved this when he saw two serpents fighting. Placing the rod between them and using his eloquence he reconciled the serpents, who then embraced each other, and becoming attached to the rod formed the caduceus. The pine cone is credited with health giving power, and the wings symbolize speed and the flight of thoughts between friends. This ancient talisman was supposed to be a charm fo prosperity, rendering its possessor healthy, wealthy and wise.
Your Charm for Today
This aspect is need of some pampering, you are in need of some pampering and who better to do it than yourself? Do something extravagant, something out of character and make this aspect a more pleasant place to be.
This is a Roman amulet and was worn for many centuries as a charm to attract good fortune. The Cornucopia represents Amaitheia’s Horn, and is a symbol of prosperity, abundance and fruitfulness. Amaltheia daughter of Melissus, King of Crete, nursed the infant Jupiter with goats milk. Jupiter afterwards endowed the goats horn with magical properties, and promising that it would supply in abundance whatever she desired, gave it to his nurse. The idea most probably originated from using the horns of oxen and goats as drinking cups.