Jupiter was recently hit by a giant space rock and astronomer @jose.luis_pereira (Instagram) was lucky enough to capture the impact in this incredible footage.
Encounters like this always remind me of our relative fragility on planet Earth. Although Jupiter’s gravity protects us from more frequent large impacts, there’s an inevitability when it comes to future encounters with big space rocks. You need only glance up at the Moon for clear evidence of this destructive heritage.
The statistics of space rock encounters are both reassuring (in terms of long timescales) but also gravely concerning (in terms of raw destructive power).
On average, every few hundred years, the Earth is hit by an object some 30-60 meters in diameter. Such an impact generates enough energy to devastate an entire city if the final shockwave is concentrated in the right position and direction. The 2013 Chelyabinsk and 1908 Tunguska events are recent example of such encounters.
Then every 10,000 years we’re hit by a 200-500 meter wide object, large enough to trigger short term but significant climate changes, potentially lowering global temperatures and disrupting crop growth and finely balanced ecological systems.
Then every million years a 2-4 kilometer wide impact can occur, releasing energy equivalent to the explosive output of every nuclear weapon on the planet!
Finally on a hundred million year timescale Earth can be visited by something like the Chicxulub event that wiped out the dinosaurs, an object some 10-20 kilometres across. That’s enough destructive power to wipe out vast swathes of life across the entire planet.
As a species we’re only a few million years old and our recorded history takes us back a paltry 10,000 years. It makes you wonder therefore, what unrecorded and long forgotten destructive encounters our distant ancestors experienced and survived? Or is our species yet to be challenged by any of the bigger impacts mentioned above?
I’m very happy to announce the launch of the 2021 Star Stories astronomy programme up at Abriachan Forest on October 30th.
If it’s clear I look forward to guiding you under Abriachan’s Milky Way class dark skies. Otherwise I’ll present an indoor talk on the naked eye planets, covering their observational history right up to the advent of modern astronomy.
Meanwhile the Abriachan team will host an outdoor walk and talk about Bats. A creature of darkness so very appropriate for our first dark sky astronomy event.
Tickets will go on sale September 30th. Please follow my Facebook page for the latest.
The 2021 Perseids meteor shower is now underway with peak activity predicted in the early morning of August 11th, 12th and 13th.
The best times to view the shower will be close to and after midnight, when the Perseus radiant is rising higher in the East. However, you don’t need to look at the radiant to see shooting stars as they’ll appear to come from all directions.
This year a thin crescent Moon won’t impact the shower and will have set in the west before proper darkness sets in. Look out for Jupiter and Saturn burning brightly on the southern horizon as you wait for shooting stars.
Observing the Perseids
You don’t need any special equipment to view a meteor shower, in fact binoculars or telescopes will just narrow your field of view. Grab a deck chair or camping mat and (if it’s cold) a warm blanket and lay out under the darkest conditions you can find, preferably away from urban light pollution. It’s an excellent activity to do alone, with family and friends, or if you have children they’ll love an excuse to get outside for some after dark play.
Put away any lights or bright mobile phone screens and simply look up and wait. Remember it takes up to 30 minutes for your eyes to fully dark adapt and any exposure to bright lights will start the process all over again. If you need a light, red LEDs or touches are best for preserving you night vision.
For optimal viewing, head out close to midnight or in the darkness of the pre dawn sky., when the radiant is highest in the sky.
Don’t Expect Too Much
You need to be patient with meteor showers. Sometimes you’ll see many and other times very few or none at all. Think of it as a great excuse to get out under the stars and take in some fresh air. Even if you don’t see much you probably won’t regret heading out and looking up. Very rarely meteor showers can erupt into storms, like the Leonids in 1833 when over 100,000 shooting stars criss crossed the night sky!
What Causes a Meteor Shower
Meteors are the fine dust and particulates left over from comets and large asteroids which stray into our solar system. Some of these are on predictable orbits and as they whizz around the Sun they melt and shed some of this material into space. The Earth then travels through these giant dust trails as it orbits the Sun, producing predictable meteor showers. The Perseids are generated by Comet Swift-Tuttle, which has a 133 year orbit.
Photographing the Perseids
If your have a DSLR camera and tripod, or a suitable phone app like NightCap, you could try capturing some meteors with this rough guide.
Firmly attach your camera or phone to the tripod.
Disable autofocus and manually focus on some bright stars (make them as small and pin point as possible in your viewing screen)
Set an ISO range somewhere between 1000-3000 depending on the capabilities of the sensor. Mid 1000s is a good middle road.
Turn off noise reduction or you’ll get big delays between each shot.
Point your camera at a high and clear part of the sky.
Shoot long exposures ranging from 10s to 30s, or simply use a remote shutter to take long manual exposures. Note: don’t go crazy with very long exposures or you’ll get amp glow from the sensor.
Take lots and lots of shots and be patient!
If your camera has a time-lapse feature you can automate the shooting process and tell the camera to continually shoot 30 second exposures over a long interval. Just watch out for dew forming on the lens if conditions are cold. Some hand warmers stuffed into a sock wrapped around the lens will solve this particular issue.
One of the most amazing parting shots of the planet Pluto, backlit by our distant Sun. Taken by the New Horizons probe as it rushed away from the planet in 2015. Look closely and Plutonian mountains can be seen casting long shadows through the hazy blue atmosphere.
As of now Pluto is the only trans-Neptunian object with a known atmosphere.