Niijima island spews jets of steam and ash near Nishinoshima island on November 21. Niijima emerged about 500 meters from the older Nishinoshima in November, and now they are one, according to NASA's Earth Observatory.
Two volcanic craters are shown on Niijima on November 22. The island emerged about 1,000 kilometers (600 miles) south of Tokyo in the Ogasawara Islands, also known as the Bonin Islands.
Niijima is seen behind Nishinoshima on November 26.
The Advanced Land Imager on NASA's Earth Observing-1 satellite captured this natural-color image of the two islands on December 8.
Niijima, bottom right, and Nishinoshima are seen conjoined on December 26.
This satellite image of volcanic activity, collected on December 31, shows Niijima merging with Nishinoshima.
On March 30, the Operational Land Imager on the Landsat 8 satellite captured this image of the combined island. The merged island is now slightly more than six-tenths of a mile across.