In the music world, there are two phrases which can at the same time inspire excitement and trepidation in all but the most diehard of a band’s fans: “side project” and “going solo.”

On Friday, Rolling Stone reported two things about the bearded wonder-band of indie folk/alternative: Fleet Foxes.

First, that drummer J. Tillman is leaving the band.

Second, that two other members of the group, Casey Wescott and Christian Wargo, have announced they will be releasing new music under a side project called Poor Moon in the form of an EP on March 27. Wescott and Wargo will still be members of Fleet Foxes.

I do not think that Tillman’s departure, though definitely unfortunate, will have a significant negative impact on Fleet Foxes’s ability to continue to create outstanding music.

Instead, the wild card in this situation will be Poor Moon and its potential effect on Fleet Foxes. Now, when two members of a band such as Fleet Foxes decide to participate in a side project, fans can be confident that the spin-off band will most likely feature some resemblance to the airy and rustic melodies which have made the group so well-loved.

The question is: will this new side project negatively impact Fleet Foxes by dividing the attentions of two band members?

There have certainly been enough side projects and solo albums in popular music over the years from which to draw information.

And what history seems to indicate is that the original band often continues to do just fine. It is the side projects and solo albums, on the other hand, that sometimes languish, perhaps because of a lack of fan crossover from the original band to the spin-off.

One band which has spawned very publicized side projects has been Blink-182. One example was Box Car Racer, in which Travis Barker and Tom DeLonge participated from around 2001 to 2002, before the band’s brief existence came to an end.

During Blink-182’s later hiatus, Barker went on to form 44 and DeLonge formed Angels & Airwaves.

Though both bands got a fair amount of attention, they did not necessarily inspire the same sized following of Blink-182.

And after Blink-182 was revived, 44 went on “hiatus,” which to many fans is the more open-ended equivalent of a “goodbye.” Angels & Airwaves is still reportedly making new projects, but I doubt they will make as big of an impact now that Blink-182 is back.

Two more examples of side projects and solo albums which didn’t exactly take off were headed by Mike Shinoda of Linkin Park and Pat Monahan of Train.

Mike Shinoda was the driving force behind Fort Minor, which released one album, “The Rising Tied”. And though there were indeed a couple hit songs on the album (“Where’d You Go” and “Remember the Name” for those keeping score at home), the 2005 LP was Fort Minor’s one and only release.

Pat Monahan is the lead vocalist for Train, which burst onto the popular music scene in 2009 (for the record, I have been a fan since “Drops of Jupiter” in 2001) with “Hey, Soul Sister,” otherwise known as that song from just about every commercial in 2010.

But during Train’s thankfully temporary hiatus from around 2006 to 2009, Monahan made his own solo album titled “Last of Seven.” And though Monahan’s voice is arguably the primary defining characteristic of Train’s sound, the solo album didn’t quite gain a secure foothold with listeners.

Now, this is not all to say that side projects cannot work out. The frontman of Sigur Rós (I hope you can contain your shock at my umpteenth mention of my Icelandic dream band), “Jónsi” Birgisson, has been very active both in terms of a side project and solo work, and Sigur Rós is apparently expected to emerge from its hiatus with a new album this spring.

His minimalist side project, “Jónsi & Alex,” released an excellent album titled “Riceboy Sleeps” but has not released another album.

Where Jónsi really made another mark on the music world is in his solo work, his album “Go” receiving praise both from fans and critics alike. He has also gone on to compose the soundtrack for the recent film “We Bought a Zoo.”

So yes, side projects are wild cards, and they can understandably release some butterflies into the stomachs of music fans. Most recently, those butterflies are flying around in the stomachs of Fleet Foxes’ fans.

But they need not worry themselves too much, in my opinion. Time will tell the fate of Poor Moon, but we can all rest easy and be confident that Fleet Foxes’ intricate melodies and harmonies will continue to entrance for years to come.

What is your favorite side project, past or present?

Email Bain at abain@media.ucla.edu.

“B-sides” runs every Monday.