SY meaning in Academic & Science ?

Answer: What is Solar Year mean?

A tropical year (also known as a solar year) is the time that the Sun takes to return to the same position in the cycle of seasons, as seen from Earth; for example, the time from vernal equinox to vernal equinox, or from summer solstice to summer solstice. This differs from the time it takes Earth to complete one full orbit around the Sun as measured with respect to the fixed stars (the sidereal year) by about 20 minutes because of the precession of the equinoxes.

Since antiquity, astronomers have progressively refined the definition of the tropical year. The entry for "year, tropical" in the Astronomical Almanac Online Glossary states:

the period of time for the ecliptic longitude of the Sun to increase 360 degrees. Since the Sun's ecliptic longitude is measured with respect to the equinox, the tropical year comprises a complete cycle of seasons, and its length is approximated in the long term by the civil (Gregorian) calendar. The mean tropical year is approximately 365 days, 5 hours, 48 minutes, 45 seconds.

An equivalent, more descriptive, definition is "The natural basis for computing passing tropical years is the mean longitude of the Sun reckoned from the precessionally moving equinox (the dynamical equinox or equinox of date). Whenever the longitude reaches a multiple of 360 degrees the mean Sun crosses the vernal equinox and a new tropical year begins".

The mean tropical year in 2000 was 365.24219 ephemeris days; each ephemeris day lasting 86,400 SI seconds. This is 365.24217 mean solar days. For this reason, the calendar year is an approximation of the solar year: the Gregorian calendar (with its rules for catch-up leap days) is designed so as to resynchronise the calendar year with the solar year at regular intervals.

reference

Full Form	Category
Second Year	Academic & Science
Solar Year	Academic & Science
Sybase, Inc.	Business
School Year	Community
Smokey Yunick	Community
Sahaja Yoga	Community
Sonic Youth	Community
Solar Yellow	General
Sugar Year	General
Slight Yellowing	General
South Yorkshire	General
Stem Y	General
Sheldon Yoko	General
Stretching and yawning	General
Sausage Yogert	General
Sincerely Yours	General
Scientist Years	General
Section Y	General
Shoot Yourself	General
Sarah Yurish	General
Silas You	General
So Yeon	General
Shang You	General
Sordid Years	General
Station Yard	General
Saul Youssef	General
Seasonal Year	General
Structures Yj	General
Sylvania East	Governmental
Sylvania West	Governmental
Security Yard	Governmental
Solicitation Year	Governmental
Ship's Yoeman	Governmental
Square Yards	Governmental
SIRKAZHI	Indian Railway Station
Square Yard	Measurement Unit
Symptom	Medical
Sexy Young	Messaging
Syria	Regional
Shoulder Yaw	Space Science
System	Space Science
Sailing Yacht	Sports