Thursday, June 29, 2017

Astronomers detect orbital motion in a pair of supermassive black holes



The picture above is an artist’s conception of the pair of supermassive black holes at the centre of the galaxy 0402+379, 750 million light-years from Earth. Credit: Josh Valenzuela/University of New Mexico.


Astronomers have detected the orbital motion in a pair of supermassive black holes in a galaxy some 750 million light-years from Earth. The two black holes, with a combined mass 15 billion times that of the Sun, are likely separated by only about 24 light-years, extremely close for such a system.

Astronomers made this discovery using the supersharp radio “vision” of the National Science Foundation’s Very Long Baseline Array. This is considered the first pair of black holes to be seen as separate objects that are moving with respect to each other, and thus makes this the first black-hole ‘visual binary.’”

Supermassive black holes, with millions or billions of times the mass of the Sun, reside at the cores of most galaxies. The presence of two such monsters at the center of a single galaxy means that the galaxy merged with another sometime in the past. In such cases, the two black holes themselves may eventually merge in an event that would produce gravitational waves that ripple across the universe.
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Tuesday, June 27, 2017

Every full moon is different!


The so-called 'Strawberry Moon' rises behind Glastonbury Tor on in June 2016.  Credit: Matt Cardy/Getty Images & The Telegraph

The Moon is the largest and brightest object in our night sky and has enchanted and inspired mankind for centuries.

Here's everything you need to know about Earth's only natural satellite, including all its different names and the dates you can spot the next one, including June's Strawberry Moon.

How often does a full moon occur?

A full moon occurs every 29.5 days and is when the Moon is completely illuminated by the Sun's rays. It occurs when Earth is directly aligned between the Sun and the Moon.

Why do full moons have names?

The early Native Americans didn't record time using months of the Julian or Gregorian calendar. Instead tribes gave each full moon a nickname to keep track of the seasons and lunar months.

Most of the names relate to an activity or an event that took place at the time in each location. However, it wasn't a uniform system and tribes tended to name and count moons differently. Some, for example, counted four seasons a year while others counted five. Others defined a year as 12 moons, while others said there were 13.

Colonial Americans adopted some of the moon names and applied them to their own calendar system which is why they're still in existence today, according to the Farmer’s Almanac.

January: Wolf Moon

This moon was named because villagers used to hear packs of wolves howling in hunger around this time of the year. It's other name is the Old Moon.

When? January 12

February: Snow Moon

Snow moon is named after the white stuff because historically it's always been the snowiest month in America. It's also traditionally referred to as the Hunger Moon, because hunting was very difficult in snowy conditions.

When? February 11

March: Worm Moon

As temperatures warm, earthworm casts begin to appear and birds begin finding food. It's also known as Sap Moon, Crow Moon and Lenten Moon.

When? March 12

April: Pink Moon

April's full moon is known as the Pink Moon, but don't be fooled into thinking it will turn pink. It's actually named after pink wildflowers, which appear in the US and Canada in early spring.

This moon - which you can see around 07:08 on Tuesday April 11 -  is also known as Egg Moon, due to spring egg-laying season. Some coastal tribes referred to it as Fish Moon because it appeared at the same time as the shad swimming upstream.

This moon is important because it used to fix the date of Easter, which is always the first Sunday after the Pink Moon appears. This year, Easter falls on Sunday, April 16.  The Pink Moon also heralds the beginning of Jewish Passover.

When? April 11

May: Flower Moon

Spring has officially sprung by the time May arrives, and flowers and colourful blooms dot the landscape.

This moon is also known as Corn Planting Moon, as crops are sown in time for harvest, or Bright Moon because this full moon is known to be one of the brightest. Some people refer to it as Milk Moon.

When?  May 10

June: Strawberry Moon

This moon is named after the beginning of the strawberry picking season. It's other names are Rose Moon, Hot Moon, or Hay Moon as hay is typically harvested around now.

This moon appears in the same month as the summer solstice, the longest day of the year (June 21st) in which we can enjoy approximately 17 hours of daylight.

When? June 9

July: Thunder Moon

Named due to the prevalence of summer thunderstorms. It's sometimes referred to as the Full Buck Moon because at this time of the year, a buck's antlers are fully grown.

When? July 9

August: Sturgeon Moon

Tribes in North America typically caught Sturgeon during this month, but also it is when grain and corn were gathered so is also referred to as Grain Moon.

When? August 7

September: Harvest Moon

It was during September that most of the crops were harvested. This moon also gave light to farmers working through the night. Some tribes also called it the Barley Moon.

The Harvest Moon can sometimes occur in October - whichever Moon is closest to the autumnal equinox.

When? September 6

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