“NASA has ruled it out. Professional and amateur astronomers are able to track Near Earth Objects (NEOs) such as Apophis and submit their observations to the NEODyS program in Italy. The number and quality of observations determines the level of certainty. The result is 100 percent certainty that Apophis will not impact Earth in the next 100 years based on the observations of Apophis’ orbits.”
Ms. Hanover says, “Well, that is certainly a relief. But isn’t it possible that something unforeseen like solar wind or a solar flare would move the asteroid?”
“Yes. This is called the Yarkovsky Effect. Asteroids rotate in space as they are traveling. The asteroid’s surface absorbs heat. How much it absorbs depends on factors such as the asteroid’s composition, its surface features, and how fast it is rotating. As the asteroid heats and cools, its orbit is affected. NASA has already included the Yarkovsky Effect in its calculations.
“As you can imagine, this gets very complex. NASA currently has a spacecraft called OSIRIS-REx studying the Yarkovsky Effect. The spacecraft was launched in 2016. It was observing the asteroid Bennu. OSIRIS-REx revolved around Bennu for years, taking pictures and measurements. It was able to obtain a sample of the asteroid in November, 2020 and it is scheduled to arrive back on Earth on September 24, 2023.”
“Wow, it is good to hear that NASA is being proactive and doing research on asteroids and NEOs. Is there anything else that we should be aware of? Any other factors that could affect Apophis or other NEOs?”
Dr. Hays reflects for a moment.
He says, “Since you asked about solar flares, there is one area of concern that is unpredictable.”
Ms. Hanover’s eyes raise and she swallows and smiles. She says, “Have you been holding out on us?”
“Well, the chance of it affecting Apophis is so small that NASA has not brought it forward as a concern to the public.” “OK, what is that?”
“The Sun has eruptions larger than the common solar flare. This cycle on the Sun consists of 11 years of increase and decrease in activity. The next ‘solar maximum’--the time the sun experiences its peak activity--is July, 2025. By that time Apophis will be much closer to us and closer to the Sun. If there was a massive solar eruption aimed toward Earth, it’s reasonable to think that it could alter the orbit of Apophis.”
Ms. Hanover blinks, looks over to her crew, and then back again to Dr. Hays.
She says, “What you just said pretty well negates NASA’s 100% certainty predictions. We don’t know what will happen in 2025.” She pauses. “Am I clear on that?”
“Yes, but a consequential solar flare could happen most any time. The greatest degree of chance to affect Apophis would be from 2024 to 2026, I would say.”
Ms. Hanover interrupts Dr. Hays and says, “This has been a tragic day with meteorites falling around the state without warning! They produced massive amounts of damage and now we learn that the 2025 solar maximum could produce any number of surprises that could force Apophis into a path toward Earth. Thank you, Dr. Hays, for your expert knowledge and insight into all things astronomical.”