The 365 Days of Astronomy Travelers in the Night Eps. 327 & 328: Suddenly Bright & The Heat is On
Aug 31, 2025
Discover the astonishing story of 2017 AG5, a massive space rock that unexpectedly brightened the skies and was tracked worldwide. At 370 feet, it poses a close approach risk to Earth, reminiscent of a cosmic surprise. The conversation also dives into alarming climate data, revealing 2016 as the hottest year on record, with temperatures 1.8°F above average and a staggering 7.2°F increase in the Arctic. A vivid reminder of how human activity is accelerating climate change, making both topics essential for our future.
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Surprising Discovery Of 2017 AG5
- Dr. Al Grauer describes discovering a bright moving object with the Catalina Sky Survey telescope that turned out to be a large near-Earth asteroid.
- The object, later named 2017 AG5, brightened dramatically and was tracked worldwide over 64 hours by 45 observatories.
Sunward Approaches Can Mask Threats
- 2017 AG5 approached from the Sun's direction, hiding most of its illuminated side and making it hard to detect before close approach.
- Its geometry caused a >250-fold brightening in nine days as it crossed Earth's orbit and presented its lit side to us.
Limited Visibility Of Recurrent Approachers
- 2017 AG5 has a 571-day orbit and is visible to current telescopes only about 60 days per close approach.
- Over 136 years it will have multiple close approaches to Earth, Mars, and the Moon but is not currently on an impact trajectory.