The Princeton University Orchestra started the year off with a musical bang this past weekend, with a concert program that belied the fact that the school year began less than two months ago. Conductor Michael Pratt led an orchestra chock full of players this year in a program of Paul Lansky, Mozart, and most impressively, Gustav Holst’s The Planets, one of the most complex works in the orchestral repertory.

Friday night’s performance at Richardson Auditorium (the program was repeated Saturday night) showed the orchestra increasing in size from small to large as the concert progressed, with Paul Lansky’s Line and Shadow scored for a scaled-down instrumental ensemble. The somewhat impressionistic one-movement piece began with low flutes, and its palette of musical colors and effects, together with the accessibility of the work as a whole, seemed to complement Mr. Lansky’s background in electroacoustic music. Mr. Pratt kept the orchestra subdued, allowing the syncopated rhythms and offbeat winds to speak, and the orchestra only reached its full sound at the end of the piece.

Mr. Pratt carried the same musical care and chamber character to Mozart’s Violin Concerto No. 5 in A Major, with more substantial string sections (but only a pair of oboes and horns) and featuring University senior Nicolas Apter-Vidler as soloist. Mr. Apter-Vidler has been studying music for a good ten years, including at Mannes College of Music, and his poised and confident performance demonstrated his solid musical training.

Mr. Pratt began the concerto gracefully, with a light touch from the oboes and horns which was vintage Mozart. Mr. Apter-Vidler began his solo with a delicate triad and light quick vibrato as he launched into the first movement Allegro. Mr. Apter-Vidler maintained a song-like quality in the principal themes, and was perfectly in time with the rest of the strings in rhythmic passages. With clean and sweet double-stops in the cadenzas to both the first and second movements, Mr. Apter-Vidler’s playing well complemented the saucy repeated phrases and effective deceptive cadences from the rest of the ensemble. A clever and tuneful Rondo containing both popular 18th-century gypsy elements and shades of Mozart’s Marriage of Figaro (composed a decade later) closed the concerto tastefully.

The most astounding piece on the University Orchestra program was Holst’s monumental The Planets, a seven movement complex orchestral suite which expanded the University Orchestra roster to almost every instrument imaginable. Mr. Pratt expanded the string sections to a total of at least 60, and wind and brass sections added the bass instrument in almost every category.

Each movement in this work describes a different planet, assigning character and purpose to the heavenly bodies. The orchestra began Mars with precise string bowings, accompanied by low horns. The driving rhythmic motive which held the movement together was strongly sustained throughout, and the orchestral sound was well unified and certainly the loudest of the evening. The rhythm was well controlled by timpanists Isaac Ilivicky and JJ Warshaw, and the war-like intensity was eased by a melodic euphonium solo by Riley Fitzgerald. Frequently throughout the suite, horn principal Kim Fried provided solos which were pure in tone, accompanied in the Venus movement by a quartet of flutes. Also effective throughout the seven movements were periodic violin solos, sweetly played by Kate Dreyfuss, as well as wind solos played by oboist Alexa McCall and clarinetist Ryan Budnick.

Holst scored this suite for a wide range of percussive and keyboard instruments which add ethereal musical effects. Jason Nong added a celestial character from the celeste, augmented by very high bell effects played by the very busy percussion players. The most well-known of the movements contains what became a very popular English hymn, and Mr. Pratt conducted the familiar melody broadly, bringing out the grandeur of Jupiter. Two harps played by Cara Souto and Connie Wang added a bit of sparkle to certain passages, as did an offstage women’s chorus conducted by Kamna Gupta.

The Lansky and Mozart pieces were certainly enough to challenge the University Orchestra so early in the season, but The Planets clearly required the concentration and focus of every player on the stage. The University Orchestra musicians were well up to the task, and the bar has now been set very high for the year to come.