Really???
Google "Sun Red Giant" and on page 1, every single link confirms it.
Link 1, space.com: "
In approximately 5 billion years, the sun will begin the helium-burning process, turning into a red giant star."
Link2: Phys.org, "the sun has been in what is known as its main sequence, where nuclear fusion in its
core causes it to emit energy and light, keeping us here on Earth nourished.
This will last for another 4.5 – 5.5 billion years"
Link3: WIkipedia; "The Sun will exit the main sequence in approximately
5 billion years and start to turn into a red giant.[27][28] "
Link4: Astronomy.com: "
Roughly 5 billion years from now, the Sun will exhaust the hydrogen fuel in its core and start burning helium, forcing its transition into a red giant star."
Link5: Theconversation.com: "
The sun won’t die for 5 billion years ... In a few billion years, the sun will become a red giant so large that it will engulf our planet."
Link6: Futurism.com: "When the Sun becomes a fully-fledged, full grown red giant (in some 7.59 billion years"
Link7: *Universetoday: "the Sun has been in what is known as its Main Sequence, where nuclear fusion in its core causes it to emit energy and light, keeping us here on Earth nourished.
This will last for another 4.5 – 5.5 billion years"
Link8: Schoolsobservatory: "In the Sun's case, this will mean the fiery end of all the inner planets of our Solar System, which might also include the Earth; but don't worry, this won't happen
for another 5,000,000,000 years."
Link9: Discovermagazine: "
In roughly 5 billion years, the sun will run out of energy and drastically alter the solar system"
That is everything on page 1. Need I go to page 2?
Seriously mate, I only linked all of these because I had a bored spare moment, but honestly it is the accepted fact. The sun does not begin transitioning into a red giant until the hydrogen runs out and then it starts to fuse helium, and that *starts* in about 5 billion years time, not 1.5 billion. It's really not up for debate.