Unlike the real Rep. Edward J. Markey, “Ed Markey Alter” never has to comb his hair.

Alter — the Massachusetts Democrat’s online alter ego — will make his second public appearance Tuesday at a virtual hearing in Second Life, a three-dimensional online world where people create electronic representations of themselves called avatars.

When Markey presides over a subcommittee hearing about virtual worlds, his Second Life avatar will simultaneously chair the hearing in a re-creation of the Rayburn hearing room.

Created in 2003 by Linden Research Inc., Second Life allows users to meet people, purchase virtual property or dress their avatars using “Linden Dollars” or tour online reproductions of everything from Jerusalem to Jazz Age Harlem. So far, Second Life has attracted 13 million “residents,” according to Linden.

Second Life “highlights the benefits of an open, innovative Internet platform,” Markey said.

Tuesday’s hearing by the Energy and Commerce Subcommittee on Telecommunications and the Internet will focus on safety, commerce and future possibilities provided by online virtual worlds. No legislative action on the industry is in the works, according to committee staffers.

“From education and health care, to solving global problems such as climate change, to the corporate world, people who never would have interacted before have been able to come together, communicate, and collaborate online,” Markey said.

Markey’s foray into the virtual world is part of a growing trend among lawmakers and government agencies to reach the public through new technologies such as Second Life. A handful of lawmakers have dabbled in the technology themselves, according to Steve Nelson, co-founder of Clear Ink, a digital marketing firm that designs Second Life creations.

At least five current and former members of Congress — including House Speaker Nancy Pelosi, D-Calif., and former Speaker Newt Gingrich, R-Ga. (1979-99) — have Second Life avatars. Gingrich appeared on the steps of the virtual Capitol in Second Life last September to promote his new think tank — 13 years after he stood on the real Capitol steps to unveil the House GOP’s 1994 fall election promise to voters, the “Contract With America.”

Democrats celebrated their 2006 takeover of Congress in the real House chamber and in a virtual one created for them by Clear Ink.

Following Pelosi’s swearing-in, which was piped into the Second Life Congress via C-SPAN, Rep. George Miller, D-Calif., held a virtual press conference to promote the Democrats’ 100-hours agenda for the start of the 110th Congress.

Rep. Jerrold Nadler, D-N.Y., also created an avatar in June 2007 to participate in an ACLU rally on civil liberties held in both real life and Second Life. Nadler — named “Jerry Nadler Streeter” — spoke for about 20 minutes before porting out of the virtual world.

Markey became involved in Second Life late last year. When the U.N. climate change conference convened in Indonesia in December, he was unable to attend because the House was still in session. Instead of using video conferencing, Markey — who also chairs the Select Committee for Energy Independence and Global Warming — addressed the conference via Ed Markey Alter.

In a similar vein, a number of federal agencies — including the Centers for Disease Control, NASA and National Oceanic and Atmospheric Administration — have used the virtual world to reach the public in a new way.

In December 2006, NOAA’s Earth Science Research Laboratory unveiled a Second Life island — Meteora. On the island, users can fly through a hurricane to learn about weather, ride on a submarine to visit deep-sea life or hold onto a weather balloon to learn about meteorology.

Second Life can help “deliver your message in more of a storytelling fashion, which is more powerful than reading about it in a textbook,” said Eric Hackathorn, project manager of NOAA’s virtual world program. “It’s meant as much more of an interactive, experiential learning environment.”

Despite the initial interest, Markey appears to be the only lawmaker who has a continued presence in Second Life — but there could be other members flying under the radar, Clear Ink’s Nelson said.

“I talked with a number of staffers who have said they’re scouting it out on behalf of their representatives,” he said.

The subcommittee hearing is scheduled at 9:30 a.m. in 2123 Rayburn.