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The Perseid Meteor Shower Is Here!
Image Credit: NASA/Bill Ingalls
The Perseids are at their peak this week!
The Perseid meteor shower, one of the biggest meteor showers of the year, will be at its brightest early in the morning on Wednesday, August 12. Read on for some tips on how to watch the night sky this week – and to find out: what exactly are the Perseids, anyway?
Credit: NASA/Bill Ingalls
Your best chance to spot the Perseids will be between 2 AM and dawn (local time) the morning of August 12. Find a dark spot, avoid bright lights (yes, that includes your phone) and get acclimated to the night sky.
Your eyes should be at peak viewing capacity after about 30 minutes; though the Moon may block out some of the dimmer meteors, you should still be able to see up to 15-20 an hour. If you’re not an early bird, you can try and take a look soon after sunset (around 9 PM) on the 11th, though you may not see as many Perseids then.
Credit: NASA/MEO
If it’s too cloudy, or too bright, to go skywatching where you are, you can try again Wednesday or Thursday night – or just stay indoors and watch the Perseids online!
Our Meteor Watch program will be livestreaming the Perseids from Huntsville, Alabama on Facebook (weather permitting), [link to come] starting around 9 p.m. EDT on August 11 and continuing through sunrise.
So… why are they called the Perseids?
Because all of a meteor shower’s meteors have similar orbits, they appear to come from the same place in the sky – a point called the radiant.
The radiant for the Perseids, as you might guess from the name, is in the constellation Perseus, found near Aries and Taurus in the night sky.
But they’re not actually coming from Perseus, right?
Credit: NASA/Joel Kowsky
Right! The Perseids are actually fragments of the comet Swift-Tuttle, which orbits within our solar system.
If you want to learn more about the Perseids, visit our Watch the Skies blog or check out our monthly “What’s Up” video series. Happy viewing!
Make sure to follow us on Tumblr for your regular dose of space: http://nasa.tumblr.com
BMW M3 Interior | via
Sea Level Rise is on the Rise
As our planet warms, sea levels are rising around the world – and are doing so at an accelerating rate. Currently, global sea level is rising about an eighth of an inch every year.
That may seem insignificant, but it’s 30% more than when NASA launched its first satellite mission to measure ocean heights in 1992 – less than 30 years ago. And people already feel the impacts, as seemingly small increments of sea level rise become big problems along coastlines worldwide.
Higher global temperatures cause our seas to rise, but how? And why are seas rising at a faster and faster rate? There are two main reasons: melting ice and warming waters.
The Ice We See Is Getting Pretty Thin
About two-thirds of global sea level rise comes from melting glaciers and ice sheets, the vast expanses of ice that cover Antarctica and Greenland. In Greenland, most of that ice melt is caused by warmer air temperatures that melt the upper surface of ice sheets, and when giant chunks of ice crack off of the ends of glaciers, adding to the ocean.
In Antarctica – where temperatures stay low year-round – most of the ice loss happens at the edges of glaciers. Warmer ocean water and warmer air meet at the glaciers’ edges, eating away at the floating ice sheets there.
NASA can measure these changes from space. With data from the Ice, Cloud and land Elevation Satellite-2, or ICESat-2, scientists can measure the height of ice sheets to within a fraction of an inch. Since 2006, an average of 318 gigatons of ice per year has melted from Greenland and Antarctica’s ice sheets. To get a sense of how big that is: just one gigaton is enough to cover New York City’s Central Park in ice 1,000 feet deep – almost as tall as the Chrysler Building.
With the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission – a partnership with the German Research Centre for Geosciences – scientists can calculate the mass of ice lost from these vast expanses across Greenland and Antarctica.
It’s not just glaciers in Antarctica and Greenland that are melting, though. Nearly all glaciers have been melting in the last decade, including those in Alaska, High Mountain Asia, South America, and the Canadian Arctic. Because these smaller glaciers are melting quickly, they contribute about the same amount to sea level rise as meltwater from massive ice sheets.
The Water’s Getting Warm
As seawater warms, it takes up more space. When water molecules get warmer, the atoms in those molecules vibrate faster, expanding the volume they take up. This phenomenon is called thermal expansion. It’s an incredibly tiny change in the size of a single water molecule, but added across all the water molecules in all of Earth’s oceans – a single drop contains well over a billion billion molecules – it accounts for about a third of global sea level rise.
So Much to See
While sea level is rising globally, it’s not the same across the planet. Sea levels are rising about an eighth of an inch per year on average worldwide. But some areas may see triple that rate, some may not observe any changes, and some may even experience a drop in sea level. These differences are due to ocean currents, mixing, upwelling of cold water from the deep ocean, winds, movements of heat and freshwater, and Earth’s gravitational pull moving water around. When ice melts from Greenland, for example, the drop in mass decreases the gravitational pull from the ice sheet, causing water to slosh to the shores of South America.
That’s where our view from space comes in. We’re launching Sentinel-6 Michael Freilich, an international partnership satellite, to continue our decades-long record of global sea level rise.
This is São Paulo at 3 PM today
No, this is not just a dark storm cloud
It's smoke
Just this year the deforestation rate of the Amazon rainforest rose more than 60%. This is a direct consequence of Jair Bolsonaro's government, treating the forest as an area of exploitation and not preservation, attempting to cease the rights of our indigenous population and straight up lying and censoring data
Our forest is dying and nobody cares
Time to get away… with her…
Motivations are likely to be multifactorial and may be influenced by individual or organizational biases and competing interests.
An additional contributing factor is that individuals may be motivated to share information that they perceive to be both accurate and of social value.
武田玲奈
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