Bright Lights, Big Sky

Q. Can you suggest locations where I'm most likely to see the Northern Lights? How about tours?

Karen Deneroff, Oakton

A. The colored light show known as the Aurora Borealis or Northern Lights can be seen hovering at least 60 miles above the Earth's surface on an almost nightly basis in some parts of the world. Generally, head for north of 60 degrees latitude.

To see the lights at their best, you need dark, clear nights, and parts of Alaska, Canada and Scandinavia are the places to go. Sadly, scientists have recently noted that Alaska may lose its Northern Lights in the next 50 years, as the north magnetic pole (a key part of the whole lights thing) is speedily heading away from North America toward Siberia. But for now, you can head to Fairbanks, Alaska.

Lights "can be seen here an average of 243 days out of the year," said Karen Lundquist, public relations manager at the Fairbanks Convention and Visitors Bureau. "It's definitely a very surreal experience. I've seen people cry and cheer." Have patience and more than a day (you never know when cloud cover will show up). Tours generally head for an established site around 10 p.m., where folks hang out until 2 or 3 a.m. For a vetted list of companies offering tours and acommodations, check the What to Do category under both "aurora viewing" and "snow sports and winter activities" (800-327-5774, http://www.explorefairbanks.com/ ).

Canada offers spectacular lights viewing in the Northwest Territories. A six-night trip in March -- complete with astronomy lectures and dog-sledding -- with Arctic Odysseys (800-574-3021, http://www.arcticodysseys.com/ ) starts at $3,995 per person double, plus airfare to Edmonton. For more info, check with Northwest Territories Tourism: 867-873-7200, http://www.explorenwt.com/ .

Want to leave North America? Try Iceland. Through April 30, California-based Scantours (800-223-7226, http://www.scantours.com ) has a two-night trip to view the lights near Lake Myvatn, a short flight from Reykjavik, starting at $765 per person double, plus airfare from the States. Iceland doesn't have a lock on Nordic Northern lights, though: Check with the Scandinavian Tourist Board ( http://www.goscandinavia.com/ ) http:// for links to the Web sites for each country.

I'll be traveling to Peru (Lima, Cuzco, Machu Picchu) on a tour. I've heard conflicting tales regarding preventative shots before traveling. What shots do I need?

Judy Herman, Fort Lauderdale, Fla.

The reason you've heard conflicting tales is that it not only depends on where you're traveling but who you are: Personal physical history is an integral part of the equation where prescriptions are concerned. The key to figuring out the madness is distinguishing between required vs. recommended, and with your itinerary, there are no required immunizations, according to the U.S. Centers for Disease Control and Prevention (CDC).

But you're not puncture-free yet. The CDC recommends that all adults and children regardless of travel plans be up to date on what are considered routine shots, and that includes tetanus-diphtheria and measles-mumps-rubella (see http://www.cdc.gov/travel for a complete list).

As your itinerary is limited to Lima, Cuzco and Machu Picchu, according to the CDC you don't need the yellow fever vaccine. Erik Mederos, an assistant at PromPeru (866-661-7378, http://www.peru.info/ ), the official tourism organization, concurs. Unless you're headed to the Amazon, he said, you "don't need any shots." But if there's a chance that you may travel east of the Andes, or to any jungle areas, every traveler over 9 months old must be vaccinated in compliance with the World Health Organization's International Health Regulations.

With your itinerary, malarial prophylaxis aren't needed; elsewhere in the country they are. And even if it's not a requirement for entry, other vaccines that can be recommended for travel to tropical South America include hepatitis A and typhoid. (In addition to Peru, tropical South America includes Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Paraguay, Suriname and Venezuela.)

At any rate, there's no substitute for talking with your doctor or visiting a travel medicine clinic at least four to six weeks before departure to figure out the best course of vaccinations. In addition to country-by-country vaccination recommendations, the CDC (877-394-8747, http://www.cdc.gov/travel ) maintains a list of travel clinics and departments of health by state.

Send queries by e-mail (travelqa@ washpost.com), fax (202-912-3609) or U.S. mail (Travel Q&A, Washington Post Travel Section, 1150 15th St. NW, Washington, D.C. 20071). Please include your name and home town.