The existence of a secondary stream of neutral atoms inside the heliosphere arriving from about 285° ecliptic longitude, which is about 30° higher than the nominal upstream direction of the inflowing interstellar gas, has been proposed recently based on a wide variety of observations from many different missions. We will discuss the LENA/IMAGE measurements in detail and conclude that the secondary stream is composed mainly of hydrogen atoms at an energy of about 1 keV. We will discuss some possible explanations for the origin of the secondary stream, with the most likely source being the region upstream of the termination shock. © 2004 American Institute of Physics