Flags across the country were set to be flown at half-staff Thursday in honor of the late John Glenn, who in 1962 became the first American to orbit the planet. President Donald Trump issued a proclamation this week ordering the lowering of the flags "as a mark of respect" in the astronaut's memory.

Glenn, who died in December, was set to be buried Thursday morning in Arlington National Cemetery.

Read: Astronaut Stephen Hawking? Richard Branson Is Bringing Famous Physicist To Space

"By the authority vested in me by the Constitution and the laws of the United States of America, that on the day of his interment, the flag of the United States shall be flown at half‑staff at the White House and upon all public buildings and grounds, at all military posts and naval stations, and on all naval vessels of the federal government in the District of Columbia and throughout the United States and its territories and possessions until sunset on such day," Trump wrote. "I also direct that the flag shall be flown at half-staff for the same period at all United States embassies, legations, consular offices and other facilities abroad, including all military facilities and naval vessels and stations."

Glenn died at age 95, decades after he served in the military, circled the Earth three times, was elected a senator in Ohio and became the oldest person in space. He left behind a legacy honored not only by Trump but also several governors who also ordered state flags to be lowered Thursday, including Connecticut Gov. Dannel Malloy and Delaware Gov. John Carney.

Trump's predecessor, President Barack Obama, requested flags be flown at half-staff at the time of Glenn's death in keeping with the Flag Code, which allows lowered flags "upon the death of principal figures of the United States government and the governor of a state, territory, or possession, as a mark of respect to their memory."

Read: John Glenn Quotes: 10 Memorable Sayings From The First American Astronaut To Orbit Earth

"John always had the right stuff, inspiring generations of scientists, engineers and astronauts who will take us to Mars and beyond — not just to visit, but to stay," Obama said in a statement last year. "The last of America's first astronauts has left us, but propelled by their example we know that our future here on Earth compels us to keep reaching for the heavens. On behalf of a grateful nation, Godspeed, John Glenn."

Watch a live stream of Glenn's memorial service here.