د. أيمن كرديDr Kordi

Today's #WinterSolstice marks the longest night of the year. https://usat.ly/2B3eS8d pic.twitter.com/O27mvRlrQS

Today is the #WinterSolstice with winter officially beginning in the Northern Hemisphere at 11:48 am ET. The sun's rays are most direct over the Tropic of Capricorn in the Southern Hemisphere and will gradually migrate north over the coming months.pic.twitter.com/oAlbcwIh3c

The actual time of the solstice varies each year, moving ahead by 6 hours until it resets every Leap Year. Winter Solstice, from the Latin sol and sister, means the sun standing still. Happy #WinterSolstice #SummerSolsticepic.twitter.com/qEItpLtoxI

If the Earth was flat , there would be no #WinterSolstice or #SummerSolstice . #Sciencepic.twitter.com/EMibfIyv1i

Today is the #WinterSolstice, which is also the shortest day of the year! What are solstices & equinoxes, and why do they occur? Get the answers: http://go.nasa.gov/2Bg1aPv pic.twitter.com/0F9V2o3EE6

Happy #WinterSolstice! Did you know that the winter solstice is actually a moment in time? This year it falls a little before 4.30pm in Greenwich, London. Find out more: http://bit.ly/Winter-solstice pic.twitter.com/bPA7vgm3v7

رافقت الفضاء عشر سنين، هي أول مركبة فضائية أقلعت للدوران حول كوكب عطارد لنتعرف عليها من خلال الانفوغراف التالي. http://nasainarabic.net/r/i/1103  #مسنجر #عطاردpic.twitter.com/1IopIK68WU

#ذكرى_البيعة_الثالثة قَوْمٌ هُمُ زِيْنَةُ الدُّنيا وَبَهْجَتُها وَهَمْ لَهَا عَمَدٌ مَمْدُودَةُ الطُّنُبِpic.twitter.com/JoQiZiQI3V

A bright sungrazing comet is currently racing to a toasty demise, with a stunning backdrop of the Milky Way, two planets, and the solar corona! [Composite of @USNRL LASCO C2/C3 + EIT, via @ESA/@NASA SOHO https://sohowww.nascom.nasa.gov/data/realtime-images.html …]pic.twitter.com/02Wkv8rS7h

Neptune was the first planet to be discovered through mathematical calculations rather than astronomical observationpic.twitter.com/jRNrwzk8yO

Tonight's Target: Orion points to Procyonpic.twitter.com/DkKDghOYXj

We capture the fusion of two big galaxiesin the early Universe. They are 12,800 million light-years from Earth and their destiny is to be one single massive galaxy. #Astronomypic.twitter.com/3uMgJiCFdi

#APCalculus #Calculus teachers! Introducing integration ideas with freehand functions in @geogebra's graphing app #mtbos #iteachmath @ohioctm @swoctm1 Give it a try: https://ggbm.at/vVXHdNWu  See how: http://screencast-o-matic.com/watch/cblY2r2Naa …pic.twitter.com/yJFxEnFB3u

Live long and prosper, Voyagers. After 40 years NASA’s twin Voyager probes continue to influence film, television and music. https://go.nasa.gov/2kLRLrT  #TuesdayThoughtspic.twitter.com/rOcdaTYv4n