Horse 2020 - The phrase "Reach For The Stars" is much older than that.

Reach for the stars is an interesting phrase. Must be from a time before people knew they were gigantic balls of plasma. Or is it a curse?

— Brendan Daly (@bjd) October 31, 2015

The phrase "reach for the stars" is indeed an interesting phrase. I've heard it in several contexts but my two most favourite are either:
1. When someone in a Western (usually an outlaw) points a gun at someone and tells them to "reach for the stars". In this context they want them to put their hands up; both as a way to make sure they they don't reach for any weapon to retaliate and because is makes it easier to perform a walletectomy of their victim.
2. As a sign of encouragement, the phrase "reach for the stars" is telling someone to aim high. It was Norman Vincent Peale, the author of that most famous of books The Power of Positive Thinking (1996) who wrote “Shoot for the moon. Even if you miss, you'll land among the stars.”

The phrase is much older than that.

Related is the phrase "Reach for the Sky" which was a 1956 film based on the 1954 biographical book written by Paul Brickhill about RAF fighter pilot Sir Douglas Bader.

Bader had been an RAF pilot since 1928 but suffered a crash in 1931 whilst attempting some aerobatic maneuvers and lost the use of his legs. He was retired against his will and when hostilities broke out in 1939, he again joined the RAF and would go on to score 20 kills, 4 shared kills, 6 probables and damaged a further 11 aircraft. He was shot down himself and would be sent to Colditz prisoner of war camp where he would eventually be liberated by the US Army in 1945. As you'd expect though, being an RAF pilot...

The phrase is much older than that.

The Latin motto "Per ardua ad astra" is the motto of several Commonwealth airforces including the Royal Australian Air Force, Royal New Zealand Air Force, Royal Canadian Air Force and the South African Air Force but it was the Royal Flying Corps which eventually became the Royal Air Force which adopted it in 1912.

It has been suggested that the first commander in charge of the RAF, Colonel Frederick Sykes, asked his officers to come up with a motto as a way of boosting morale. King George V is reported to have liked it immensely. The officer generally credited with it is Lieutenant J. S. Yule, who was walking across Farnborough Airport with a friend at the time.
As you'd expect...

The phrase is much older than that.

As most people in the upper echelons of society at the turn of the 20th century were still educated in the classics of Greek and Latin, Lt Yule had read it in Virgil's epic poem The Aeneid. The Aeneid speak of Aeneas' journey from his home in Troy to Italy, where he would settle and eventually give rise to the Roman Empire.
The Aeneid dates from no earlier than about 19BC. Aeneas was already a well known character and appears in Homer's The Illiad; which itself dates from about 710BC.

In Latin the phrase "Macte nova virtute, puer: sic itur ad astra, dis genite et geniture deos." is said by the god Apollo to Aeneas's son Iulus and translates as "Go forth with new value, boy: thus is the path to the stars; son of gods that will have gods as sons." after Iulis has just killed one of the Italians, Numanus, despite having no war experience whatsoever and perhaps doing it by accident with a stray arrow.

Is the phrase to "reach for the stars" from a time before people knew they were gigantic balls of plasma? YES!
We now live in an age where even small children know that the sun is a mass of a mass of incandescent gas; a gigantic nuclear furnace, where hydrogen is built into helium, at a temperature of millions of degrees. Some say... that The B-Side to this song will be familiar to fans of a certain British Motoring Show, and that it was all the plan of a particular untamed racing driver to smash all the equipment in that hotel kitchen which closed it, so that Mr Clarkson wouldn’t get a hot meal, in a ploy to take over as the next host of the show.
All we know is... that "Reach for the Stars" is such an interesting phrase that it takes 7 people to sing about it.