Astronomers and skywatchers alike are abuzz with excitement over an extremely rare celestial event predicted to briefly dim one of the brightest stars visible in Earth’s night sky next week.
On December 11-12, the bright red supergiant star Betelgeuse in the constellation Orion is expected to experience a remarkable occultation as it’s covered by a small asteroid known as 319 Leona. This will cause the tenth-brightest star in the sky to dramatically fade in brightness for a few short hours.
Lead-Up to the Rare Betelgeuse Occultation
Betelgeuse has attracted intense scientific interest in recent years after the brilliant star underwent an unprecedented dimming event starting in late 2019, fading to about 40% of its usual brightness for several months before recovering in 2020.
Astronomers continue working to decipher the cause of what became known as the “Great Dimming” of Betelgeuse. Potential explanations range from huge star spots driven by convection changes in the aging star’s complex atmosphere, to expulsions of large amounts of dusty stellar material temporarily blocking its light.
Table 1: Basic Facts on Betelgeuse
|Red supergiant star
|Distance from Earth
|~728 light years
|11.6 times the Sun’s mass
|5,800°F / 3,200°C
|150,000 times the Sun’s luminosity
Now, scientists and amateur astronomers will have another rare chance to analyze Betelgeuse’s brightness fluctuations as the reddish giant goes through an asteroid occultation on December 11th into the 12th.
While stars can often be seen winking out briefly due to occultations by small solar system bodies like asteroids, the last time Betelgeuse was covered to such a degree was September 17, 1993. Given Betelgeuse’s position in Orion where occultation events are less common, this is an exceedingly rare phenomenon generating substantial interest.
What Will Happen During the Betelgeuse Occultation
The asteroid responsible for the imminent occultation is known as 319 Leona. Discovered in 1891, Leona is relatively small at just 18 miles wide, but will perfectly align to eclipse the massive Betelgeuse star from Earth’s viewpoint next week.
Observers of the occultation across the southeastern United States as well as parts of Central America and northern South America will witness Betelgeuse dramatically disappear behind Leona for a few hours on the night of December 11th into the early morning hours of December 12th.
Northern Africa and southern Europe will also have visibility during the roughly three to four-hour occultation window, weather permitting. Locations with the best viewing prospects are highlighted in the map below, although the visibility region is dependent on local weather conditions on the key date.
Image showing parts of the world that will have visibility of the rare Betelgeuse occultation event on Dec 11-12. Credit: International Occultation Timing Association
Over the next few days leading up to the occultation window on December 11th-12th, the separation in the sky between the foreground Leona asteroid and background Betelgeuse star will rapidly shrink to a fraction of an arcsecond.
Table 2: Timeline of Milestone Events During the Occultation
|First contact – Leona fully covers Betelgeuse
|Dec 11 at 5:26:30 hr
|Mid-eclipse – Maximum dimming of Betelgeuse
|Dec 11 at 7:17:55 hr
|Last contact – Leona finishes passing Betelgeuse
|Dec 12 at 0:56:33 hr
|Betelgeuse returns to normal brightness
|Dec 12 at 1:27:28 hr
Once the occultation begins and Leona starts transiting Betelgeuse, the star is predicted to diminish drastically to just 0.05% of its normal luminosity over a roughly 10 minute period. It will then remain extremely faint for about 3 to 4 hours before emerging from behind the asteroid early on December 12th and gradually regaining its typical brilliance afterward over 30-45 minutes.
“The thrill of witnessing such a rare alignment of an asteroid directly in front of one of the most famous stars in the sky will make this an unforgettable event,” notes astronomy professor Dr. Zena Trottier. “Scientifically tracking Betelgeuse’s brightness fluctuations during all stages of the occultation will also let researchers glean new insights into the physics of this unstable aging star.”
Importance for Follow-Up Study of Betelgeuse’s Behavior
Given the immense scale of Betelgeuse, astronomers anticipate the supernova explosion marking the end of the star’s life cycle will likely occur somewhere within the next 100,000 years and be easily visible during daytime on Earth. The star’s eventual death is expected to leave behind an exotic neutron star remnant.
Researchers will carefully analyze Betelgeuse before, during and after next week’s occultation event to expand understanding of the star’s variability and pulsation mechanisms. Comparing brightness readings to the last observable occultation in 1993 will also prove interesting.
“Capturing multiwavelength observations spanning visible light, infrared, and radio emissions during this rare alignment will give us new pieces to the puzzle on what drove Betelgeuse’s Great Dimming a few years ago and what instabilities the star is undergoing as it nears the end of its evolution,” said Dr. Trottier.
A range of ground and space telescopes are gearing up to intently monitor Betelgeuse over the next week, along with legions of citizen scientists and amateur astronomy groups eagerly anticipating what should be a once-in-a-lifetime celestial spectacle.
How to Watch Next Week’s Rare Occultation Event
Although the December 11th-12th occultation window will be brief, the extreme rarity of the event is drawing attention from astronomers far and wide. “Don’t miss your chance to witness one of the brightest stars in our sky essentially disappear,” exclaims astronomy professor Dr. Richard Harvuot.
While Betelgeuse should remain clearly visible to the naked eye across the southeastern U.S. and parts of the Americas throughout the multi-hour occultation, observers everywhere are encouraged to watch online broadcasts documenting the phenomenon.
Virtual access to research telescope feeds tracking Betelgeuse’s dimming will allow global participation. Some free live streams providing occultation visibility include:
Additionally, photography and observations by astrophotographers situated near the visibility path can help analyze brightness measurements both during and around the key occultation period.
“Combining such visual recordings and scientific data gives us the best chance to unlock more insights on not just Betelgeuse’s own instability, but also the fate that awaits all stars in the final chapter of their lifetimes,” said Dr. Harvuot.
So ready your telescopes, cameras, and live stream apps to witness an extremely rare cosmic alignment over the coming week. One of the most luminous stars gracing planet Earth’s night sky is poised to temporarily vanish and create an amazing memory for all lucky viewers.
What Happens Next for Betelgeuse After the Occultation
Once Betelgeuse emerges from behind asteroid Leona by December 12th and returns to its typical brilliance high overhead in Orion, astronomers will continue tracking the unstable supergiant using collected data to refine stellar models.
Further observations over the next few months will determine whether the rare occultation has any noticeable short-term effects on Betelgeuse as it adjusts from the temporary interference of the dimming event.
But while this nearby star is sure to remain under continued study after again dominating Orion’s right shoulder, the years ahead will see Betelgeuse marching ever closer toward supernova demise.
When that finally occurs no earlier than ~100,000 years in the future, the supernova’s violent burst is expected to shine as brightly as the full Moon for over a month. It would be a remarkable sight and leave behind an exotic neutron star remnant.
“For now Betelgeuse still has ample life left to go through more pulsation cycles and mass ejections,” said Dr. Trottier. “But catching fleeting alignments like next week’s remarkable occultation gives us better understanding of the fate that awaits Betelgeuse and other aging stars in the long run.”
So enjoy the stellar show during astronomy’s Super Bowl moment this December!
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