H meaning in Space Science ?

Answer:

What is Hours mean?

An hour (symbol: h; also abbreviated hr) is a unit of time conventionally reckoned as 1⁄24 of a day and scientifically reckoned as 3,599–3,601 seconds, depending on conditions. There are 60 minutes in an hour, and 24 hours in a day.

The hour was initially established in the ancient Near East as a variable measure of 1⁄12 of the night or daytime. Such seasonal, temporal, or unequal hours varied by season and latitude.

Equal or equinoctial hours were taken as 1⁄24 of the day as measured from noon to noon; the minor seasonal variations of this unit were eventually smoothed by making it 1⁄24 of the mean solar day. Since this unit was not constant due to long term variations in the Earth's rotation, the hour was finally separated from the Earth's rotation and defined in terms of the atomic or physical second.

In the modern metric system, hours are an accepted unit of time defined as 3,600 atomic seconds. However, on rare occasions an hour may incorporate a positive or negative leap second, making it last 3,599 or 3,601 seconds, in order to keep it within 0.9 seconds of UT1, which is based on measurements of the mean solar day.

reference

Full Form	Category
Humanities	Academic & Science
Hall	Academic & Science
Harvard	Academic & Science
Honors	Academic & Science
Handle	Academic & Science
Hyperion	Business
Hydrogen	Chemistry
Horrific	Community
Highlighted	Community
Humility	Community
Hebrew	Community
Heaven	Community
Holy	Community
Hilfiger	Community
Harmony	Community
Home-school	Community
Hoax	Computing
Hilly	Earth Science
Heater	Electronics
Form H (break; Break) Contacts	Electronics
Henry	Electronics
Hybrid	Electronics
Hell	General
Harry	General
Howard	General
Hannah	General
Hector	General
Horatio	General
Horace	General
Hog	General
Horse	General
Ham	General
And How	General
Harrison	General
Harriet	General
Helen	General
Hope	General
Heads	General
Harold	General
Helpful	Governmental
Homicide	Governmental
Hospital	Governmental
VENKATAGIRI KOTE HAL	Indian Railway Station
Hicri	International
Hilarious	Internet
Hobo	Jobs
Hamming	Maths
Half	Measurement Unit
Hypodermic	Medical
Hematachometer	Medical
Heart	Medical
Heterosexual	Medical
Haploid	Medical
Hospitalization	Medical
Hearing	Medical
Health	Medical
Histidine	Medical
mustard gas	Medical
Hands	Medical
health and safety	Medical
hysterectomy and sterilisation	Medical
Hepatitis	Medical
Huggable	Messaging
Hmm	Messaging
Huh??	Messaging
Hero	Military and Defence
Undistilled Sulfur Mustard Gas (military Designation)	Military and Defence
Honesty	Military and Defence
Honor	Military and Defence
Hub	Networking
Husband	Real Estate
Header	Softwares
Height (altitude)	Space Science
Head	Space Science
Horizontal	Space Science
Hot	Space Science
Hours	Space Science
Hockey	Sports
Hits	Sports
Hits against	Sports
Hidden	Sports
Hint	Sports
The Hogs	Sports
Hardball	Sports