A partial solar eclipse will occur on September 21, 2025, offering a celestial spectacle for a small fraction of the world's population. For everyone else, the event will be broadcast live and for free online, with coverage beginning at 2 p.m. EDT (1800 GMT).
The livestream ensures that viewers globally can witness the Moon pass in front of the Sun without needing to be in the direct path of visibility, which is limited to remote island nations in the Pacific Ocean.
Key Takeaways
- Event: A partial solar eclipse will take place on September 21-22, 2025.
- Livestream: A free online broadcast will be available, starting at 2 p.m. EDT (1800 GMT).
- Maximum Eclipse: The peak of the event is expected at 3:41 p.m. EDT (1941 GMT).
- Visibility: The eclipse will only be directly visible from New Zealand, Samoa, Tonga, and other nearby islands.
- Safety: It is never safe to view a partial solar eclipse with the naked eye; proper eye protection is mandatory for direct viewing.
Understanding the Celestial Event
A partial solar eclipse happens when the Moon moves between the Sun and Earth, but the three bodies are not perfectly aligned. From our perspective, the Moon obscures only a portion of the Sun's disk, creating the appearance of a dark bite taken out of our star.
Unlike a total solar eclipse, where the Moon completely blocks the Sun, a partial eclipse leaves a crescent of the Sun visible. The amount of the Sun covered depends on the viewer's location within the eclipse path.
What Determines an Eclipse's Path?
The visibility of a solar eclipse is confined to a relatively narrow path on Earth's surface. This path is determined by the alignment of the Sun, Moon, and Earth, and the specific shadow cone (the umbra and penumbra) that the Moon casts upon our planet. For the September 21 event, this shadow will primarily cross the southern Pacific Ocean.
Details of the September 21 Eclipse
The upcoming partial solar eclipse is a significant astronomical event, though its direct visibility is highly restricted. The path of the eclipse means that very few people will be able to witness it firsthand.
A Rare Viewing Opportunity
According to astronomical data, fewer than 17 million people will be in the eclipse's path of totality. This represents just 0.2% of the global population, making the online livestream the primary viewing method for most of the world.
For those in the viewing area, particularly in New Zealand, the eclipse will be a remarkable sight. The event will begin as the Sun rises, with a portion of its disk already obscured by the Moon. At the point of maximum eclipse, observers in New Zealand will see over 70% of the Sun covered by the lunar silhouette.
Key Timings for the Eclipse
- Livestream Begins: 2:00 p.m. EDT (1800 GMT) on September 21.
- Maximum Eclipse Occurs: 3:41 p.m. EDT (1941 GMT).
These times are crucial for anyone planning to tune into the live broadcast to ensure they don't miss the peak of the celestial alignment.
How to Watch the Livestream from Home
Thanks to a collaboration between Time and Date and the Dunedin Astronomical Society in New Zealand, a high-quality, free livestream will be accessible to a global audience. The broadcast will provide real-time video feeds of the eclipse from various viewpoints.
This initiative allows people from all continents to experience the event safely and with expert guidance. The stream will be hosted on YouTube, making it easily accessible on computers, smartphones, and smart TVs.
"The broadcast will feature real-time views of each phase, paired with expert commentary provided by astrophysicist Graham Jones and journalist Anne Buckle."
The commentators will explain the different phases of the eclipse, discuss the science behind the phenomenon, and answer viewer questions. This educational component adds significant value for those new to astronomy.
Crucial Safety for Eclipse Viewing
While the livestream offers a perfectly safe way to watch, it is vital to reiterate the dangers for anyone who might be in the eclipse's direct path. Looking directly at the Sun, even when it is partially covered, can cause immediate and permanent eye damage, including blindness.
Standard sunglasses, no matter how dark, are not sufficient to protect your eyes. The intense solar radiation can burn the retina without causing any pain, leading to a condition known as solar retinopathy.
Why is a Partial Eclipse So Dangerous?
During a partial eclipse, the Sun remains intensely bright. The natural human instinct to squint or look away is reduced because the overall brightness is lower, but the focused ultraviolet and infrared radiation can still cause severe harm. Only specially designed solar filters or eclipse glasses that are ISO 12312-2 certified should ever be used for direct viewing.
Safe Viewing Methods
- Certified Eclipse Glasses: Use glasses that meet the ISO 12312-2 international safety standard.
- Pinhole Projector: A simple and safe way to project an image of the Sun onto a surface.
- Telescopes with Solar Filters: Never look through a telescope, binoculars, or camera lens without a professionally made solar filter attached to the front.
- Online Livestream: The safest and most accessible method for the vast majority of people.
The risk of clouds is always a factor for ground-based astronomy. The livestream organizers are hoping for clear skies over New Zealand, but the broadcast will proceed regardless, providing commentary and alternative feeds if available.
