The regime's state-run Korean Central News Agency said the satellite, named Kwangmyongsong-3, was "fitted with survey and communications devices essential for the observation of the earth."
The satellite itself is probably not very sophisticated, said David Wright, a senior scientist with the Union of Concerned Scientists.
The regime showed it in April, and it was a small box with solar panels and a simple camera with some basic communication devices, he said.
He compared it to Sputnik 1, the first man-made satellite that Russia launched into space in 1957. The value lies in the launch rather than in the object that North Korea now has floating above the Earth, Wright said.
The regime doesn't "really care so much what's in it." It's a statement, Wright said.
In Japan and South Korea, people will hear about North Korea's achievement -- and will probably be struck by its power, he said.
Any show of might can help strengthen North Korea's position in international talks on numerous issues, including nuclear negotiations.
The South Korean government said the launch was confrontational and a "threat to the peace and stability of the Korean Peninsula and the world." Japan called it "intolerable."
Iran praises the launch as much of the world assails it
Iran, meanwhile, praised North Korea's move.
Gen. Masoud Jazaeri, a senior Iranian military official, expressed happiness about the launch, the semiofficial Fars News Agency reported.
"Experience has shown that independent countries, by self-confidence and perseverance, can quickly reach the height of self-sufficiency in science and technology. Hegemonic powers, such as the United States, are unable to stop the progress of such countries," he said.
China expressed regret that the launch had taken place, noting "concerns among the international community."
"We hope relevant parties stay calm in order to maintain peace and stability on the Korean Peninsula," said Hong Lei, a Chinese Foreign Ministry spokesman.
Several governments criticized Pyongyang's decision to spend hundreds of millions of dollars on its rocket program rather than on assisting its poor, malnourished population.
British Foreign Secretary William Hague said he deplored the fact that North Korea "has chosen to prioritize this launch over improving the livelihood of its people."
The North's failed launch in April ended a deal for the United States to provide thousands of tons of food aid to the country.
In his father's footsteps
"I think this is very important to Kim Jong Un to build political legitimacy and bolster the spirits of his people," said James Schoff, a North Korea specialist with the Carnegie Endowment for International Peace. "He is doing this despite the fact that he knows he is going to come into a lot of criticism in the region for it."
The launch has taken place during a period of power consolidation for Kim in which he has purged senior military officers in an apparent effort to stamp his authority on the regime's leadership.
"If Kim Jong Un pulls off a successful long-range missile test, it's a very important signal saying that 'Yes, I, Kim Jong Un, have replaced the powerful generals,' " said John Park, a Stanton junior faculty fellow at the Massachusetts Institute of Technology. "It shows that 'I have found the right balance and I am now in charge.' "
The launch also ties in with important dates for the regime's ruling dynasty.
Pyongyang had said this rocket launch would be "true to the behests" of Kim Jong Il, the late North Korean leader and father of Kim Jong Un.
Kim Jong Il died on December 17 last year, so the rocket launch took place just days before tearful mourners are expected to gather for the first anniversary of his death.
Experts had also speculated that North Korea wanted this launch to happen before the end of 2012, the year that marks the centenary of the birth of Kim Il Sung, the founder of North Korea and grandfather of Kim Jong Un.