Explained: Light in the sky over California

FRESNO, Calif. (KFSN) -- Many in the Central Valley saw a bright light in the sky on Saturday night. The U.S. Navy said the light was from an unarmed Trident II D5 missile, but many people still have questions about how what they saw could be a missile.

Here are some of the questions and observations that were posted on social media regarding the incident:

Observation: The Navy said they launched the missile from a submarine, but I saw it fly from the south (or the southeast) to the west (or northwest) over land -- not over water.

Explanation: The U.S. Navy said the missile was launched from the Pacific Test Range, a vast area northwest of Los Angeles where the Navy periodically test-fires Tomahawk and Standard cruise missiles from surface ships and submarines. However, the Navy Air Systems Command describes this area as being located at Point Mugu -- just South of Oxnard -- and extending into 36,000 square miles of ocean to the northwest.

Looking at a map, Santa Barbara is due south of Fresno. Point Magu is south, and slightly east of Fresno. In the Central Valley, this creates an illusion that the missile traveled over land -- when in fact it did not.

Question: Why didn't the military notify the public before the launch?

Answer: Cmdr. Ryan Perry, a Navy spokesman, told the Associated Press the launch was classified.

Loren Thompson, a military analyst with the Lexington Institute, told the L.A. Times the Trident II (D5) missile is a centerpiece of the U.S. military ability to deter a nuclear attack. They keep the tests secret to thwart efforts by Russia or China -- or any other adversaries -- to monitor the missile in flight.

Question: If it was a missile launched in California, how was it seen in Florida?

Answer: It was not seen in Florida. The pictures that reportedly show the missile launch in Florida is actually from a September 2nd launch of an Atlas V rocket. Some people on social media confused those images with pictures from the launch in California.

The launch was clearly seen in Arizona and as far away as Salt Lake City.

Question: If that was a missile launch, why was it so bright? Why is it so different from other videos of a Trident II (D5) missile launch?

Answer: The missile launched after 6 p.m. on Saturday night -- a little over an hour after sunset. The missile was launched high enough for the sun to reflect off the rocket and illuminate the trailing plume.

John Daniels told the L.A. Times said this made the missile appear brighter, more difficult to discern, and visible for long that it would have been during the day or night.

Missile launches just before dawn, or just after sunset can create quite a spectacle as the projectile, and the plume is illuminated by the sun while everything else remains dark.

Josefina Alvarado

Missile launch photography tips

About the Trident II D5 missile:

Primary Function: Strategic Nuclear Deterrence.
Contractor: Lockheed Missiles and Space Co., Inc., Sunnyvale, CA.
Date Deployed: 1990.
Unit Cost: $30.9 million (in 2009)

Propulsion: Three-stage solid-propellant rocket.
Length: 44 feet (13.41 meters).
Diameter: 83 inches (2.11 meters).
Weight: 130,000 pounds (58,500 kg).
Range: Greater than 4,000 nautical miles (4,600 statute miles, or 7,360 km).
Guidance System: Inertial.
Warhead: Nuclear MIRV (Multiple Independently Targetable Re-entry Vehicles).

More information: www.lockheedmartin.com

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