When is it curtains for our solar system?

Q: As our sun dies, what will happen to the planets, especially our own?

In about 5 billion years, scientists estimate, the Earth will be engulfed and burned up in the expanding radius of the sun as it evolves.

This event will be about 1 million years after Venus and Mercury "have suffered the same fate," according to updated calculations published in 2008 in the journal Monthly Notices of the Royal Astronomical Society. It will also be long after the Earth becomes too hot to support life.

As the sun ages into a red giant, it will expand, losing mass and cooling somewhat, but remaining very hot.

"While solar-mass loss alone would allow the orbital radius of planet Earth to grow sufficiently to avoid this 'doomsday' scenario," the authors of the study conclude, the tidal interaction of the sun and the closely orbiting planet "will lead to a fatal decrease" in the size of Earth's orbit.

At least some of the outer planets may survive, scientists suggest.

But the authors of the study note that "there is no immediate hurry to implement the scheme."

Q: We have a winter jasmine that blooms in the coldest weather. What insects are active in January and February to pollinate the flowers?

"Many of the plants we see blooming at this time of year don't get pollinated," said Kerry Barringer, curator of the herbarium at the Brooklyn Botanic Garden. "Most of them, like your winter jasmine, Jasminum nudiflorum, are not native to this area and are not adapted to our seasons and our pollinators."

When winter jasmine blooms in central China, where it is native, there are moths, flies and small bees to pollinate it, Barringer said, but when it blooms in the Northeastern United States, pollinators are mostly dormant.

"A stretch of warm days can bring out some flies and beetles, but most of our pollinating insects are not active," he said.

Barringer listed other winter bloomers, including the Chinese witch-hazels, Japanese camellias and some of the Japanese viburnums and cherries.

Most native species are dormant, waiting for warmer days. Those that bloom in late winter often have special adaptations for pollination. Some red maples, Acer rubrum, can be pollinated by wind as well as insects.

The skunk cabbage, Symplocarpus foetidus, has "flowers that actually heat up to provide a warm haven for the flies that pollinate it," Barringer said.

They become so warm they can melt snow and ice.