The "Golden Handle" is a beautiful optical illusion that appears on the Moon's surface around 10 to 11 days after a new moon, or approximately two days after the first quarter. It's a well-known phenomenon among amateur astronomers.
What is the Golden Handle?
The Golden Handle, also known as "Lunar X" or "Jeweled Handle," is a visual effect caused by sunlight illuminating the peaks of the Montes Jura mountain range while the surrounding low-lying plain of Sinus Iridum (the Bay of Rainbows) is still in shadow. This creates a bright, arc-shaped outline that appears to extend into the unlit, night side of the Moon, resembling a handle made of golden light.
Galileo Galilei himself was aware of this phenomenon and used his observations to estimate the altitude of lunar mountains!
When to see it (Tonight, July 5, 2025):
The Golden Handle is expected to be visible tonight, Saturday, July 5, 2025. It typically appears a couple of days into the waxing gibbous phase. On this date, the moon will be in its waxing gibbous phase, about 10 days old, with approximately 76.5% illumination.
Look for the waxing gibbous moon hanging above the southern horizon as the sun sets. The phenomenon is best observed shortly after sunset, as the moon rises and the sky darkens.
How to see it:
Location: Look for the Moon in the northwest region of its surface, close to the terminator (the line dividing light from dark). Specifically, locate the Montes Jura mountain range bordering Sinus Iridum's northern edge.
Naked Eye: While sharp-eyed observers might be able to faintly discern a tiny bulge from the terminator with the naked eye, the Golden Handle is best viewed with optical aid.
Binoculars: A good pair of binoculars (e.g., 15x70 mounted on a tripod) will help you clearly see the sweeping profile of the Golden Handle.
Telescope: A telescope with an aperture of 6 inches or greater will provide an even more detailed view of Montes Jura and nearby features like the Bianchini Crater. Start with a low magnification to get an overview, then increase magnification to observe the illuminated mountain peaks in more detail.
This is a fleeting but spectacular sight, so make sure to take the opportunity to observe it tonight!