Are the following bold sentences considered all as an opinions?

-Geographers and historians have traditionally held the view that Antarctica was first sighted around 1820, but some sixteenth-century European maps show a body that resembles the polar landmass, even though explorers of the period never saw it. Some scholars, therefore, argue that the continent must have been discovered and mapped by the ancients, whose maps are known to have served as models for the European cartographers.

-Scientists formerly believed that the rocky planets were created by the rapid gravitational collapse of a dust cloud, a deflation giving rise to a dense orb. That view was challenged in the 1960s, when studies of Moon craters revealed that these craters were caused by the impact of objects that were in great abundance about 4.5 billion years ago but whose number appeared to have quickly decreased shortly thereafter. This observation rejuvenated Otto Schmidt’s 1944 theory of accretion. According to this theory, cosmic dust gradually lumped into ever-larger conglomerates: particulates, gravel, small and then larger balls, planetesimals (tiny planets), and, ultimately, planets. As the planetesimals became larger, their numbers decreased. Consequently, the number of collisions between planetesimals decreased.

-According to mutual fund sales experts, a successful year for a stock fund should result not only in increased investor dollars flowing into the fund, but also in increased investor dollars flowing into other mutual stock funds offered by the same company.
However, while last year the Grafton Mutual Company’s “Growth Stock Fund” beat average market returns by a factor of two and recorded substantial new investment, the other stock funds offered by Grafton did not report any increase whatsoever.

-Many People believe that Christopher Columbus was the first European to visit North America. This is grossly untrue, There is well-documented evidence that Leif Erickson and the Vikings visited North America centuries earlier, as well as hypotheses that others even preceded Erickson.

-Scientists agree that …..
-Most scientists think that …..
-Most scientists believe that …


Furthermore, What if the bolded part started after believe/agree that:

-Geographers and historians have traditionally held the view thatAntarctica was first sighted around 1820, but some sixteenth-century European maps show a body that resembles the polar landmass……
-Scientists formerly believed that the rocky planets were created by the rapid gravitational collapse of a dust cloud, a deflation giving rise to a dense orb. That view was challenged in the 1960s, when studies of Moon craters revealed that these …….
-Many People believe that Christopher Columbus was the first European to visit North America.
-According to mutual fund sales experts, a successful year for a stock fund should result not only in...

will these portions now become facts or still claims/beliefs??

thanks