Astronomy Picture of the Day – Perseid Fireball and Persistent Train 

Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2018 August 17

Perseid Fireball and Persistent Train 
Image Credit & Copyright: Petr Horálek


Explanation: Before local midnight on August 12, this brilliant Perseid meteor flashed above the Poloniny Dark Sky Park, Slovakia, planet Earth. Streaking beside the summer Milky Way, its initial color is likely due to the shower meteor’s characteristically high speed. Moving at about 60 kilometers per second, Perseid meteors can excite green emission from oxygen atoms while passing through the thin atmosphere at high altitudes. Also characteristic of bright meteors, this Perseid left a lingering visible trail known as a persistent train, wafting in the upper atmosphere. Its development is followed in the inset frames, exposures separated by one minute and shown at the scale of the original image. Compared to the brief flash of the meteor, the wraith-like trail really is persistent. After an hour faint remnants of this one could still be traced, expanding to over 80 degrees on the sky.


Your Earth Sky News for August 17th: We promise you won’t be eaten by a megalodon (too cool to past up)

We promise you won’t be eaten by a megalodon

So go ahead and get scared at the new movie “The Meg,” but don’t worry. Scientists have officially debunked the myth that megalodon sharks still exist.

If you’re planning to go see the new summer blockbuster movie “The Meg” this weekend, be scared in the theater – but you don’t need to worry at the beach. Scientists have officially debunked the myth that megalodon sharks still exist. The whale-eating monsters became extinct about 2.6 million years ago.

Catalina Pimiento, of Florida Museum of Natural History at University of Florida, is lead author of a study, published in the peer-reviewed journal PLOS ONE that determined the date of extinction for Carcharocles megalodon – the largest predatory shark to ever live. Pimiento said in a statement:

I was drawn to the study of Carcharocles megalodon’s extinction because it is fundamental to know when species became extinct to then begin to understand the causes and consequences of such an event.

I also think people who are interested in this animal deserve to know what the scientific evidence shows, especially following Discovery Channel specials that implied megalodon may still be alive.

Scientists think that megalodon looked like a stockier version of the great white shark, with strong, thick teeth, built for grabbing prey and breaking bone. Regarded as one of the largest and most powerful predators to have ever lived, fossil remains of megalodon suggest that this giant shark reached a length of about 60 feet (18 meters). Their large jaws could exert a bite force of up to 24,000 – 41,000 lbf (110,000 to 180,000 newtons).

Size comparison of Carcharodon carcharias or great white shark (green), and current maximum estimate of the largest adult size of Carcharodon megalodon (gray), with a human. Image via Wikipedia.

Pimiento said that because modern top predators, especially large sharks, are significantly declining worldwide due to the current biodiversity crisis, this study could help serve as a basis to better understand the consequences of these changes.

When you remove large sharks, then small sharks are very abundant and they consume more of the invertebrates that we humans eat. Recent estimations show that large-bodied, shallow-water species of sharks are at greatest risk among marine animals, and the overall risk of shark extinction is substantially higher than for most other vertebrates.

Pimiento plans to further investigate possible correlations between changes in megalodon’s distribution and the evolutionary trends of marine mammals, such as whales and other sharks. She said:

When we calculated the time of megalodon’s extinction, we noticed that the modern function and gigantic sizes of filter feeder whales became established around that time. Future research will investigate if megalodon’s extinction played a part in the evolution of these new classes of whales.

For the study, researchers used databases and scientific literature of the most recent megalodon records and calculated the extinction using a mathematical model.

Bottom line: Megalodon sharks are extinct.


Published on EarthSky

Your Daily Karmic Number for August 17 is 9

Daily Karmic Number

Something in your life is coming to an end. And 9 suggests that this is a happy ending. You don’t need the experience in question anymore because it has served its purpose. If you aren’t sure what it is, stop and inventory what has been taking up less of your time. Let it go. Be open to a new beginning. There is a chance that the old situation will present itself again, but you have a choice to let it pass you by when it does. This will test your determination to not repeat old habits. You will be grateful for this shift in your life.