Anniversaries, those human-created markers in time and space, call to our need to hold on to the good times and the bad, and to take stock of where we are today. Sometimes joyous, sometimes sorrowful, they speak to our need to remember what has shaped our lives and pay tribute as we can.

So around 10:10 this morning, bells will peal. Some people will stop for a moment and recall what was happening at that time two years ago. Others may not notice. Neither response will change what those moments meant for so many, when a gunman shot and killed six Tucsonans and physically wounded 13 outside a Safeway.

For some affected, the anniversary occurs every day and always will.

On paper, the case is closed. The prosecution of the murderer is complete. He pleaded guilty and will spend the rest of his life in prison - where he has finally received treatment for the schizophrenia and depression that, based on a psychologist's report, escalated in the years and months before he committed the mass shooting.

Shock and grief have prompted some who were shot, or who lost beloved spouses, children and friends that day, to join together for common-sense gun-control measures. We join in their calls for bans on extended-capacity magazines and assault-style weapons, and requiring a background check for every gun sale.

As Patricia Maisch, the woman who prevented the shooter from reloading, has pointed out, if the gunman had thrown 30 bullets at the group gathered that morning to speak with U.S. Rep. Gabrielle Giffords, the result would have been vastly different. Jan. 8, 2011, would have faded into obscurity as just another beautiful Tucson winter day.

But, as we all know, that's not what happened.

Giffords survived but left Congress and has, with her husband, Mark Kelly, become outspoken about the need to stop gun violence.

Ron Barber, who was there as Giffords' aide that day, has been elected to Congress. After 20 children and six adults were shot and killed in mid-December at a school in Newtown, Conn., Barber has been vocal about the necessity for action on gun-law reform and better treatment for people with mental illness. He joins former Giffords office colleague Pam Simon, who has partnered, along with others affected, with Mayors Against Illegal Guns.

The family of Christina-Taylor Green, who was 9 when she was killed, started the Christina-Taylor Green Memorial Foundation, which grants funds for education, art, music, student government and sports projects.

The family of Gabe Zimmerman, also a Giffords aide, has created the BEYOND organization, which organized events across the area over the weekend to honor the love of the outdoors and the community that propelled Zimmerman into public service.

Some of the victims have returned to private life. Others have made it clear that making communities safer is now their life's work. All will find their own way to continue on.

At some point, Jan. 8, 2011, will seem like history. But for many Tucsonans, it remains vivid, not faded enough to be regarded as the past.

And as long as people are working toward a safer future, and putting their energies into making our community stronger, the strength of what was put in motion that morning two years ago will continue to propel us forward.

Arizona Daily Star